Publications

a model for hormone receptor binding to the mouse mammary tumour virus regulatory element based on hydroxyl radical footprinting.	the mouse mammary tumour virus long terminal repeat region contains regulatory sequences able to mediate transcriptional induction by different steroid hormones. two clusters of binding sites for the glucocorticoid and the progesterone receptors have been identified in the region between -70 and -190, the so called hormone responsive or regulatory element. to understand the molecular details of the interaction between the receptors and the dna we have used the high resolution technique of hydrox ...	1988	2848219
construction of a clonable, infectious, and tumorigenic mouse mammary tumor virus provirus and a derivative genetic vector.	molecular genetic studies of mouse mammary tumor virus (mmtv) have been hampered by the difficulty of cloning proviruses of milk-borne strains because of inhibitory sequences located in the gag gene. to surmount this barrier we have constructed a hybrid mmtv provirus composed of clonable 5' sequences (encompassing gag) from an endogenous mmtv provirus of c3h mice (mtv-1) and 3' sequences from the milk-borne strain of mmtv in c3h mice, mmtv(c3h). virions produced from xc cells transfected with th ...	1988	2849114
towards an idiotype vaccine against mammary tumors. induction of an immune response to breast cancer-associated antigens by anti-idiotypic antibodies.	previously we have reported on the production of two sets of human monoclonal antibodies reacting with mouse mammary tumor virus (mmtv) and human mammary tumor virus (humtv) cross-reacting antigens. b11 is a monoclonal igg generated by the human-human hybridoma technique using axillary lymph node of breast cancer patients. 4.6/6 is a monoclonal igg established by the mouse-human hybridoma procedure using peripheral blood lymphocytes of a healthy investigator working with the breast cancer cell l ...	1988	2849550
requirement for the simian virus 40 small tumor antigen in tumorigenesis in transgenic mice.	to examine the role of simian virus 40 (sv40) large t and small t antigens in tumorigenesis in animals, we generated transgenic mice which expressed either both the sv40 large t and small t antigens or the sv40 large t antigen alone under the control of the mouse mammary tumor virus long terminal repeat. the mouse mammary tumor virus long terminal repeat directs the expression of transgenes in ductal epithelial cells of several organs, including the mammary gland, lung, and kidney, and in lympho ...	1988	2850490
variable responsiveness of hormone-inducible hybrid genes in different cell lines.	altered steroid responsiveness leads to various pathological conditions and is a particular problem for the treatment of cancers arising in steroid-sensitive cells. to develop cellular model systems for the analysis of the molecular mechanisms mediating altered steroid responses, we have analyzed the inducibility of a steroid-responsive promoter in different cell lines. in vitro constructs containing the mouse mammary tumor virus promoter fused to the herpes simplex virus thymidine kinase gene o ...	1988	2851100
negative regulation of transcription in vitro by a glucocorticoid response element is mediated by a trans-acting factor.	in vitro experiments with cell extracts prepared from a mouse mammary epithelial cell line demonstrated that a cis-acting glucocorticoid response element (gre) of the mouse mammary tumor virus represses transcription from its homologous promoter. competition transcription experiments, in which a molar excess of a restriction fragment that contains the gre is added to the cell-free assay, revealed that a nuclear factor mediates in trans the negative regulation of mammary tumor virus transcription ...	1988	2851730
concentration of retroviruses by low-speed centrifugation.	concentration of retroviruses from volumes of up to 6 liters of medium by low-speed centrifugation is described. in contrast to pelleting, no damage or aggregation of particles was observed. surface glycoproteins were also fully preserved. this method enables simple handling of relatively large volumes of medium. highly purified mouse mammary tumor virus (mmtv) was obtained and its transframe protein p30 in sds-page was recognized as a double band.	1988	2851744
chromatin structure of hormone-responsive moloney murine leukemia virus proviruses that contain sequences from mouse mammary tumor virus.	the chromatin structure of chimeric moloney murine leukemia viruses (m-mulvs) containing a glucocorticoid response element (gre) from mouse mammary tumor virus (mmtv) inserted into the long terminal repeat (ltr) was investigated. nuclear run-on assays indicated that transcription from the chimeric proviruses was induced 2- to 4-fold by dexamethasone. the wild-type m-mulv 5' ltr contained a dnase i hypersensitive (hs) site at the tata sequences, as well as four sites in the enhancer region. the c ...	1988	2852418
differential detection of murine mammary tumor virus constituents by immuno-electron microscopy.		1988	2855364
temperature-sensitive transport of glycoproteins to the surface of a variant mouse lymphoma cell line.	the expression of mouse mammary tumor virus (mmtv) glycoproteins on the surface of stably infected mouse lymphoma cell line w7mg1 is dramatically increased by glucocorticoid hormones. a variant cell line, w7m.ts1, was selected from w7mg1 for its lack of expression of mmtv glycoproteins on the cell surface in response to treatment with glucocorticoid. hormonal stimulation of mmtv rna levels and hormone-induced cytolysis occurred normally in the variant cells. furthermore, the rates of production ...	1988	2832739
[presence of antibodies specifically reacting with structural proteins of the mammary cancer virus among antibodies found in circulating immune complexes in patients with breast cancer].	circulating immune complexes were precipitated from breast cancer patients' sera using 2.5% polyethylene glycol. cic isolated from 70 ml of sera from 15 patients were dissociated and immunoglobulin-containing fraction was prepared by chromatography on sephadex g-200 column. the fraction contained igg specific for mumtv structural proteins, as revealed by elisa. cic preparations from 22 sera of breast cancer patients were digested with pepsin; fab' fragment preparations were also analysed by elis ...	1988	2833956
differences in progression of balb/cfriii and balb/cfc3h mammary hyperplastic alveolar nodules transplanted into the gland-free fat pads of balb/c mice.	in balb/cfc3h and balb/cfriii virgin female mice, i.e., balb/c mice carrying milk-transmitted c3h and those carrying riii murine mammary tumor virus infection, respectively, mammary noduligenesis and tumorigenesis are remarkably different. focal hyperplastic alveolar changes or hyperplastic alveolar nodules were removed from balb/cfriii or balb/cfc3h breeding female donors and transplanted into the gland-free mammary fat pads of syngeneic balb/c virgin female recipients with or without hormonal ...	1988	2835155
differential gene activation by glucocorticoids and progestins through the hormone regulatory element of mouse mammary tumor virus.	the hormone regulatory element (hre) of mouse mammary tumor virus can mediate activation of an adjacent promoter by glucocorticoids and progestins. a detailed comparison of the dna binding of receptors for both hormones using dnaase i footprinting and methylation protection detects clear differences in their interactions with the hre region between positions -130 and -100. binding studies and gene transfer experiments with a variety of mutants covering the entire hre demonstrate differences in t ...	1988	2835167
the n-terminal region of the chicken progesterone receptor specifies target gene activation.	steroid hormone receptors belong to a family of nuclear receptors that trigger transcriptional activation of target genes by specific binding to dna recognition sequences, usually located in the 5'-flanking region of the target gene. nuclear receptors appear to be segmented proteins and extensive structure-function analyses have attempted to elucidate the functional significance of individual segments. two of these regions have been defined as the domains responsible for recognition of responsiv ...	1988	2835683
amplification of the int-2 gene in primary human breast tumors.	proviral activation of the int-2 gene is a frequent occurrence in mammary carcinomas induced by mouse mammary tumor virus (mmtv). here, we have examined the human homolog of int-2 in 110 primary breast cancer dnas. the locus was amplified 2- to 15-fold in 18 of the tumor dna samples. amplification of int-2 has a highly significant association (p less than 2 x 10(-6] with tumors from patients who subsequently developed a local recurrence of the disease or a distal metastasis.	1988	2835739
glucocorticoid-regulated localization of cell surface glycoproteins in rat hepatoma cells is mediated within the golgi complex.	glucocorticoid hormones regulate the post-translational maturation and sorting of cell surface and extracellular mouse mammary tumor virus (mmtv) glycoproteins in m1.54 cells, a stably infected rat hepatoma cell line. exposure to monensin significantly reduced the proteolytic maturation and externalization of viral glycoproteins resulting in a stable cellular accumulation of a single 70,000-mr glycosylated polyprotein (designated gp70). cell surface- and intracellular-specific immunoprecipitatio ...	1988	2836430
a transcriptionally defective long terminal repeat within an endogenous copy of mouse mammary tumor virus proviral dna.	mouse mammary tumor virus proviral dna is endogenous to most inbred strains of mice but in many strains is not transcriptionally active. this inactivity may be due to defects in the proviruses themselves or to position effects mediated by dna sequences flanking the proviral units. the transcriptional competence of long terminal repeats (ltrs) derived from endogenous proviral dna at genetic loci mtv-8, mtv-9, and mtv-17 of the c57bl/6 mouse strain was examined with a transient transfection assay ...	1988	2836622
expression of human sequences related to those of mouse mammary tumor virus.	sequences related to those of the mouse mammary tumor virus (mumtv) genome have been cloned from human dna by screening a library prepared from the dna of a human breast cancer cell line with mumtv gag-pol dna. nine distinct groups of (mumtv-related) sequences were identified among 100 lambda recombinants by cross-hybridization experiments with subcloned fragments containing gag-pol-related dna. the largest group, of 64 recombinants, contains the mumtv-related sequences cloned by others. the oth ...	1988	2831381
structural and functional analysis of long terminal repeats of suncus murinus mammary tumor virus.	a 2.7-kilobase (kb) cdna sequence complementary to suncus murinus mammary tumor virus (sm-mtv) genomic rna [corrected] was prepared using purified virions produced by the sm-mt cell line, which had been established from a spontaneous mammary tumor of s. murinus. it was found, by using this cdna in southern hybridization experiments, that sm-mtv was endogenous to this animal and that some 50 copies of endogenous provirus were present per haploid cellular genome. in addition, a proviral sm-mtv dna ...	1988	2831384
phorbol diester-inducible, cyclosporine-suppressible transcription from a novel promoter within the mouse mammary tumor virus env gene.	the mouse t-cell lymphoma cell line el4.e1 constitutively synthesizes mouse mammary tumor virus (mmtv) transcripts encoding either the entire proviral genome or segments of it. in addition to these conventional mrnas, however, an mrna of about 1 kilobase accumulates after induction of these cells with phorbol myristate acetate (pma). the accumulation of this transcript is strongly inhibited by the immunosuppressive agent cyclosporin a. its pattern of induction by pma and suppression by cyclospor ...	1988	2831399
cooperativity of the glucocorticoid receptor and the caccc-box binding factor.	glucocorticoid receptor binding sites (gre) are often tightly clustered with other transcription factor binding sequences. examples of this occur upstream of the genes for chicken lysozyme and human metallothionein iia (ref. 3), in several retroviral ltrs and upstream of the rat tryptophan oxygenase (to) gene. in the to gene, sequences immediately upstream of a glucocorticoid receptor binding site are required for steroid induction and contain a caccc-box identical to that found in the beta glob ...	1988	2831456
different int-1 region dna rearrangements within different zones of a single mouse mammary tumor.	fragments were taken from separate parts of hormone-dependent (hd) primary gr mouse mammary tumors and serially transplanted in estrone plus progesterone treated or hormonally untreated castrated mice. the transplants were examined with respect to int-1 dna rearrangement, proviral integrations of the murine mammary tumor virus (mmtv), and estrogen and progesterone receptor content. one of the fragments (b) taken from the primary tumor of line tsi 96 produced transplants that showed int-1 rearran ...	1988	2831652
mouse mammary tumor proviruses from a t-cell lymphoma are associated with the retroposon l1md.	four charon 4a clones containing mouse mammary tumor virus (mmtv) proviruses and their cellular flanking sequences were obtained from partial ecori libraries of a c57bl/6 t-cell lymphoma with both endogenous and newly acquired mmtv proviruses. the cellular flanking sequences of three of four mmtv proviruses contained dna homologous to the 3' end of the long interspersed retroposon l1md. two of the three proviruses were newly acquired in the lymphoma dna, and these mmtv proviruses appeared to be ...	1988	2826809
optimized reaction conditions and specific inhibitors for initiation of transcription by rna polymerase ii in nuclei from cultured mammalian cells.	an assay that employs guanosine 5'-o-(2-thiotriphosphate) was used to measure correct initiation of rna chains in isolated cell nuclei, where chromatin structure is relatively undisturbed. rna chains initiated with guanosine 5'-o-(2-thiotriphosphate) were separated from the remaining rna by mercury-sepharose column chromatography and analyzed for correctly initiated mouse mammary tumor virus rna with a t1 nuclease protection assay. the monovalent cation concentration dependence for initiation in ...	1988	2449443
isolation and characterization of interferon-resistant variants from s49 mouse lymphoma.	s49 mouse lymphoma cells were found to be extremely sensitive to the antiproliferative activity of interferon. these characteristics were studied to select for ifn-resistant cell variants. some 0.6% of the parental s49 cell population were resistant to the antiproliferative and cytotoxic activities of ifn. the resistant cells were cloned and analyzed for their responses to several of the activities of ifn, namely, inhibition of encephalomyocarditis (emc) virus, murine leukemia virus (mulv) repli ...	1988	2455652
morphologic and antigenic properties of mouse mammary tumor virus produced in a hormone-responsive fashion by c57bl/10 mammary tumors of non-viral origin.	bl-matu/a1 mouse mammary tumor cells, derived from a c57b1/10 mammary adenocarcinoma induced by dimethylbenzanthracene and mammotropic hormones, express virus particles and proteins related to mouse mammary tumor virus (mmtv). immunocytochemical analysis by means of monospecific and monoclonal anti-gp52 sera revealed a different localization of the main structural proteins of mmtv in bl-matu/a1 and gr cells (the latter used as a positive virus-producing control). immunoelectron microscopy of b-t ...	1988	2456634
detection in the blood serum of breast cancer patients of circulating immune complexes containing antigens showing common epitopes with structural proteins of mouse mammary tumour virus (mmtv).	in the blood serum of a proportion of breast cancer patients (29.4%) immune complexes specifically reacting with the immunoglobulins of the serum against mmtv structural proteins were detected using indirect enzyme-linked immunosorbent assay (elisa). the presence of such complexes could decrease the titre of antibodies reactive with mmtv in the blood serum of breast cancer patients.	1988	2456679
the hbv x-orf encodes a transactivator: a potential factor in viral hepatocarcinogenesis.	we report here on a transactivating function of hbv dna. the effect is shown by stimulation of transient expression of psv2cat dna in cotransfected human liver ccl13 cells. transfection experiments with plasmid constructs containing different hbv dna fragments and northern analyses of rna from cells transfected with these recombinant plasmids indicate that a transactivating function is encoded within the x-orf. a frameshift mutation within the x gene causes loss of activity thus demonstrating re ...	1988	2457861
transactivating potential of the 3' open reading frame of murine mammary tumor virus.	the procaryotic chloramphenicol acetyltransferase (cat) gene controlled by the murine mammary tumor virus (mmtv) promoter shows reduced activity in a rat mammary tumor cell line after infection with mmtv but to a considerably lesser extent than the cat gene controlled by a heterologous promoter, indicating trans-acting regulation of promoter activity by mmtv. cotransfection of vectors capable of expressing rna from the 3' open reading frame (orf) of mmtv with the cat-mmtv construct resulted in e ...	1988	2459415
characterization of ribosomal frameshifting in hiv-1 gag-pol expression.	based on precedents from other retroviruses, the precursor of the human immunodeficiency virus (hiv-1) reverse transcriptase is predicted to be a polyprotein with a relative molecular mass (mr) of 160,000 (160k) encoded by both the viral pol gene and the upstream gag gene. these two genes lie in different translational reading frames, with the 3' end of gag overlapping the 5' end of pol by 205 or 241 nucleotides. thus, production of the gag-pol fusion protein would require either messenger rna p ...	1988	2447506
anti-alpha-galactosyl antibodies in chagasic patients. possible biological significance.	1. antibodies from chagasic patients (ch), bound to a column of immobilized purified glycoprotein 25-kda antigen of trypanosoma cruzi epimastigotes (gp25), were partially lytic (70% lysis at 50 micrograms/ml) to cultured metacyclic trypomastigotes (y strain) in a complement-mediated reaction (alternative pathway). 2. antibodies (ch) eluted with galactose from a melibiose-agarose column reacted in elisa titration plates with gp25, whole cells of metacyclic trypomastigotes (y strain), and less int ...	1988	2471563
expression and phenotypic alterations caused by an inducible transforming ras oncogene introduced into rat liver epithelial cells.	although transforming ras oncogenes have been implicated as causative factors in liver cell transformation, the exact function and phenotypic alterations generated by the expression of such transforming genes in liver epithelial cells has yet to be defined. we have utilized a retroviral vector system to deliver an inducible transforming ras gene into normal, anchorage dependent rat liver epithelial cells. the moloney murine sarcoma virus based vector is composed of a dominant selectable marker, ...	1988	3060790
disordered metabolism of microfilament proteins, tropomyosin and actin, in mouse mammary epithelial cells expressing the ha-ras oncogene.	synthesis of 37- and 41-kd tropomyosins (tm) is suppressed in fibroblasts expressing transforming oncogenes, which may contribute to the deranged microfilament structure seen in such cells (cooper et al., mol. cell. biol. 5, 972, 1985). to determine whether tm metabolism was also deranged when epithelial cells expressed a transforming oncogene, we studied cultured mouse mammary epithelial cells which express the activated c-ha-ras oncogene either constitutively or through glucocorticoid activati ...	1988	3060798
ras (proto)oncogene induces n-linked carbohydrate modification: temporal relationship with induction of invasive potential.	the effect of expression of the ras oncogene on protein glycosylation was studied. vsv g-protein and class i histocompatibility antigens were analysed to monitor ras-mediated changes in glycosylation. transient expression of the c-ha-ras oncogene, introduced into nih 3t3 cells by the deae-dextran method, altered protein glycosylation within 25 h of transfection. the same result was obtained after dexamethasone-induced expression of p21-ras in stable nih 3t3 transfectants containing either an act ...	1988	3061796
induction of transforming growth factor alpha expression in mouse mammary epithelial cells after transformation with a point-mutated c-ha-ras protooncogene.	nog-8 ras cells are a normal mouse mammary epithelial cell line transfected with a plasmid containing a glucocorticoid-inducible mouse mammary tumor virus long terminal repeat linked to the activated c-ha-ras protooncogene. after addition of dexamethasone, there is a rapid induction (within 1-3 h) of p21ras protein that is concomitant with a parallel induction of the c-ha-ras specific mrna. after 4-6 days of dexamethasone treatment, nog-8 ras cells are able to grow as colonies in semisolid mediu ...	1988	3063955
retroviral heterogeneity in mouse lymphomas.	provirus modifications which can occur in tumors may lead to tumor antigenic variants. to investigate this possibility we compared the restriction fragment length patterns of mouse mammary tumor virus (mmtv), murine leukemia virus and xenotropic and mink cell-focus inducing (mcf)-related sequences, using southern blot analysis, in a panel of balb/c and c57bl/6 lymphomas, some of which were known to express novel histocompatibility (h) antigens. the results indicate differences in amplification a ...	1988	2896330
single-step induction of mammary adenocarcinoma in transgenic mice bearing the activated c-neu oncogene.	we have used transgenic mice that carry an activated c-neu oncogene driven by a mouse mammary tumor virus (mmtv) promoter to assess the stepwise progression of carcinogenesis in mammary epithelium. unlike the stochastic occurrence of solitary mammary tumors in transgenic mice bearing the mmtv/c-myc or the mmtv/v-ha-ras oncogenes, transgenic mice uniformly expressing the mmtv/c-neu gene develop mammary adenocarcinomas that involve the entire epithelium in each gland. because these tumors arise sy ...	1988	2898299
unlinked regulation of the sensitivity of primary glucocorticoid-inducible responses in mouse mammary tumor virus infected fu5-5 rat hepatoma cells.	the enzyme tyrosine aminotransferase (tat) is induced by unusually low concentrations of glucocorticoids in fu5-5 cells. we have isolated clones of fu5-5 cells infected with mouse mammary tumor virus (mmtv) in order to simultaneously compare the glucocorticoid regulation of the host cell gene, tat, with that of another primary inducible gene, mmtv. in the two clones that were examined in detail, mmtv rna induction occurred at 4- to 11-fold higher concentrations of dexamethasone than those needed ...	1988	2906113
mmtv as a model for gene expression in mammary tissue.		1988	2908656
the activation of cellular oncogenes by proviral insertion in murine mammary cancer.		1988	2908657
steroid hormone regulation of cultured breast cancer cells.		1988	2908658
expression of the int-1 gene in transgenic mice is associated with mammary gland hyperplasia and adenocarcinomas in male and female mice.	transcriptional activation of the int-1 gene by proviral insertion mutations is thought to be a key step in mammary tumor induction by the mouse mammary tumor virus (mmtv). to test this hypothesis, we have constructed an int-1 allele resembling those found in virus-induced tumors, with an mmtv ltr placed 5' to the int-1 gene in the opposite transcriptional orientation. transgenic mice harboring this allele express int-1 rna at high levels in mammary and salivary glands of male and female mice an ...	1988	3180222
human progesterone a-receptors can be synthesized intracellularly and are biologically functional.	in order to investigate the origin and functional independence of the human progesterone receptor a binding protein, we have expressed a truncated human progesterone receptor cdna in both gene transfer and in vitro translation assays. proteins identical in size and antigenicity to the a-receptors found naturally in human progesterone target cells are synthesized from this cdna that lacks the putative b receptor initiator methionine codon of the complete cdna. the functional independence of a-rec ...	1988	3196338
mapping cis-dna regulatory elements in seminal vesicle secretion genes, prostate c3(1) gene, and the mouse mammary tumor virus-long terminal repeat dna.		1988	3217428
dexamethasone-dependent inhibition of differentiation of c2 myoblasts bearing steroid-inducible n-ras oncogenes.	ras proteins are localized to the plasma membrane where they are postulated to interact with growth factor receptors and other proximal elements in intracellular cascades triggered by growth factors. the molecular events associated with terminal differentiation of certain skeletal myoblasts are inhibited by specific polypeptide growth factors and by constitutive expression of transforming ras oncogenes. to determine whether the inhibitory effects of ras on myogenic differentiation were reversibl ...	1988	3133379
stimulation of specific transcription and dna binding studies suggest that in vitro transformed ru 486-glucocorticosteroid receptor complexes display agonist activity.	the relative rate of ovalbumin transcription was significantly increased (p less than 0.001) when purified chick liver glucocorticosteroid receptor (gr) was incubated with purified nuclei prepared from the oviducts of diethylstilboestrol (des)-primed chickens 24 h after oestrogen withdrawal. this increase was observed whether gr was bound by the agonist triamcinolone acetonide (ta, +80.3%) or the antiglucocorticosteroid ru 486 (+89.4%). no significant increase (p greater than 0.05) in the relati ...	1988	3386256
binding of hormone accelerates the kinetics of glucocorticoid and progesterone receptor binding to dna.	steroid hormone receptors induce genes by virtue of their interaction with dna regulatory sequences. the hormonal response of a particular gene in vivo correlates with binding of the hormone to the receptor and supposedly reflects the degree of occupancy of the corresponding dna regulatory sequences. however, in vitro the steroid-free glucocorticoid and progesterone receptors bind specifically to the regulatory sequences of mouse mammary tumor virus, thus raising questions on the role of the hor ...	1989	2919163
binding of androgen-receptor complexes to alpha 2u-globulin genes and to the long terminal repeat of mouse mammary tumor virus.	the binding of androgen-receptor complexes to fragments derived from two alpha 2u-globulin genes (rap 01 and rao 01) was studied using a dna-cellulose competition assay. rat prostate cytosol labelled with [3h]mibolerone was used as a source of the androgen receptor. two controls were included in these studies: the long terminal repeat (ltr) of mouse mammary tumor virus which has previously been shown to act as an androgen response element and a fragment of the c3 gene of prostatic binding protei ...	1989	2477291
effect of simulated american, bulgarian, and japanese human diets and of selenium supplementation on the incidence of virally induced mammary tumors in female mice.	in attempts to simulate the effects of diet on human breast cancer development groups of female c3h mice infected with mammary tumor virus (mmtv-) were maintained on diets formulated to resemble the typical american, bulgarian, and japanese human diets. the incidence of mammary tumors was the highest (84%) in group of mice receiving the simulated meat- and fat-rich american diet, which was also low in selenium (se content: 0.15 ppm). the appearance of mammary tumors was delayed in the mice maint ...	1989	2484397
a highly inducible system of gene expression by positive feedback production of glucocorticoid receptors.	to investigate the function of a cloned gene, inducible enhancer/promoters are preferred for controlling the level of expression experimentally. highly inducible gene expression systems with both low basal levels and enhanced maximal levels of expression are especially sought. we have developed a new expression system using a positive feedback mechanism. glucocorticoid receptor cdna was fused to the enhancer/promoter of mouse mammary tumor virus (mtv) to induce receptor production. simultaneous ...	1989	2494026
the purified activated glucocorticoid receptor is a homodimer.	the structure of purified preparations of activated (dna-binding) glucocorticoid receptor (gr) was analyzed in the presence or absence of dna. a 35-base pair dna fragment harboring a strong gr-binding site from the mouse mammary tumor virus promoter (-189/-166) was used for stoichiometric analysis of the gr.dna complex. glycerol gradient centrifugation was utilized in order to separate the 6 s gr.dna complex from the 4 s gr and the 3 s dna fragment. synthetic glucocorticoid [3h]triamcinolone ace ...	1989	2494184
characterization of a presecretory phase in b-cell differentiation.	we have identified and characterized an inducible in vitro subclone of the ch12 b-cell lymphoma, ch12-lbk, which appears to represent a transitional phase in the b-cell differentiation pathway. this phase, which we call the "presecretory" phase, falls between replicating b cells that are not secreting antibodies and b cells that secrete antibody at a high rate. presecretory cells are characterized by abundant steady-state levels of immunoglobulin and joining (j) chain transcripts and of protein ...	1989	2495536
int-1--a proto-oncogene involved in cell signalling.	the int-1 gene was originally identified as a locus activated by mouse mammary tumor virus insertion. cloning and sequencing of the mouse gene indicates that int-1 encodes a 41k, 370 amino acid, cysteine-rich protein with a potential hydrophobic signal peptide sequence. expression studies clearly indicate that int-1 enters the secretory pathway and is probably secreted, although definitive evidence is lacking. drosophila int-1 encodes the wingless gene, wingless, a segment-polarity gene, is requ ...	1989	2534596
isolation of a pathogenic clone of mouse mammary tumor virus.	exogenous mouse mammary tumor virus (mmtv) was cloned from a gr mammary tumor. clone lambda grt39 contained a full-length integrated mmtv(gr) provirus and both 5' and 3' host flanking dna. the lambda grt39 provirus had no apparent structural changes associated with cloning and retained the exogenous mmtv gag gene poison sequence. when introduced into rat mammary adenocarcinoma la7 cells, the lambda grt39 provirus was fully expressed. lambda grt39-transfected la7 cells made mmtv rna, had gp52 su ...	1989	2535722
amplification of mouse mammary tumor virus genomes in non-mammary tumor cells.	extra proviral copies of mouse mammary tumor virus (mmtv) are known to be present in the genomes of certain t-cell lymphomas of mice. analysis of additional non-mammary tumor cell types known to express mmtv transcripts and antigens revealed the presence of extra acquired mmtv proviruses in a pituitary tumor cell line, a macrophage line, and leydig testicular tumor cells. the nature of the amplified mmtv proviruses in these various tumor cell types differed with regard to copy number and presenc ...	1989	2535749
ultrastructural features of the intestinal absorption of mouse mammary tumor virus in newborn balb/cfriii mice.	the retrovirus mouse mammary tumor virus is present in mouse strains with a high incidence of mammary tumors as a causative agent. it is produced mainly in the mammary glands of sexually mature females and is milk-transmitted to newborns. the fate of the mouse mammary tumor virus is almost unknown. where it enters, how it is distributed, and where it remains latent, remain unresolved problems. this study tries to answer the first of these questions. viruses are for the most part digested in the ...	1989	2535827
expression of human papillomavirus type 16 e7 gene induces dna synthesis of rat 3y1 cells.	human papillomavirus type 16 (hpv 16) open reading frames (orf) e6, e7, and e6e7, placed under the control of dexamethasone-inducible mouse mammary tumor virus long terminal repeat, were introduced into rat 3y1 cells, an immortalized fibroblast line, with the aid of neomycin-selection. the cell clones containing inducible hpv 16 orfs were selected and examined for dna synthesis. following induction of hpv mrna synthesis by the hormone, dna synthesis was stimulated in the cells containing e7 or e ...	1989	2535904
a putative int domain for mouse mammary tumor virus on mouse chromosome 7 is a 5' extension of int-2.	we extended the physical map of the mouse int-2 locus by demonstrating that the site of insertion for mouse mammary tumor virus dna in plaque-type mammary tumors of gr mice is directly linked to int-2. an additional example of proviral integration is described in which a provirus in a presumed enhancer-insertion mode 15 kilobases upstream of the int-2 promoters is capable of activating expression of the gene at levels typical of other virally induced mammary tumors.	1989	2536846
estrogen influence on maturational pathway of murine mammary tumor virus: an immunoelectron microscopy study.	modifications induced by estrogens on hormone-independent murine mammary tumor (mmt) and its main etiological agent, the mmt virus (mmtv), are reported. high doses of estrogens released continuously from silastic capsules delay significantly the development of transplanted tumors into syngeneic hosts. neoplastic cells present a striking cytoplasmic vacuolization and changes in the mmtv differentiation pattern. mature virions are detected budding into cytoplasmic vacuoles instead of the extracell ...	1989	2537750
the role of sex steroids in the expression of mmtv in the normal mouse mammary gland.	infection with the mouse mammary tumor virus (mmtv) is associated with hyperplastic alveolar growth and subsequent tumorigenesis. the role of the sex steroids in the initial phase of this pathological chain of events is investigated in this study. in normal mammary epithelium, progesterone stimulates mmtv rna expression both in vivo (2.6-fold) and in vitro (2.9-fold); although estradiol is ineffective alone, it does enhance the effect of progesterone (6.8- and 5.7-fold stimulation, respectively) ...	1989	2539131
construction and characterization of a packaging cell line for mmtv-based conditional retroviral vectors.	a chimeric provirus in which the 5'ltr of a complete biologically active mouse mammary tumour virus (mmtv) proviral dna has been replaced with the rous sarcoma virus ltr has been constructed. upon transfection into permissive cells, this provirus directs the synthesis of the mmtv gag and env structural proteins, but is impaired in packaging of the rnas that encode these proteins. supertransfection of these cells with mmtv based vector constructs results in the production of infectious recombinan ...	1989	2539144
multihormone regulation of mmtv-ltr in transfected t-47-d human breast cancer cells.	multihormonal regulation on the long terminal repeat (ltr) region of mouse mammary tumour virus (mmtv) has been studied using t-47-d human breast cancer cells stably transfected with the steroid sensitive ltr-c3 chimaeric gene. the specificity of steroid action on transfected ltr sequences has been compared with regulation of endogenous cellular markers. we conclude that the hormone response element of the ltr can be induced by physiological concentrations of androgen, progestin and glucocortico ...	1989	2539537
molecular cloning and sequencing of the mtv-1 ltr: evidence for a ltr sequence alteration.	the vertically transmitted mtv-1 provirus is the primary causative factor of mammary neoplasia in certain c3hf strains that lack the horizontally transmitted mouse mammary tumor virus (mmtv). the studies here report the molecular cloning of the germ line 4.5 kb mtv-1 3' ecori fragment and sequencing of the 3' mtv-1 ltr. the mtv-1 ltr sequence is closely related to the 5' mtv-11 ltr sequence also reported here, as well as to known mtv-8 and mmtv ltr sequences in the portion of mmtv and mtv-8 ltrs ...	1989	2539705
reinfection of virus free mice with mouse mammary tumour virus.	br6/icrf mice carrying a milk-transmitted mammary tumour virus (mmtv) develop tumours after several pregnancies. if the mice are freed from mmtv, no tumours develop. in the experiments described in this paper, mmtv was reintroduced into mmtv-free mice by foster nursing, which was least effective if the pups were exposed to the virus only during the first week of life. exposure for even a short time after that age led to a tumour incidence similar to that found in normally infected mice. reinfect ...	1989	2540382
transgenic mice carrying the mouse mammary tumor virus ras fusion gene: distinct effects in various tissues.	transgenic mice carrying the v-ha-ras oncogene under the control of the mouse mammary tumor virus long terminal repeat were produced. these mice exhibit several phenotypes: mammary tumors, bilateral hyperplasia of the harderian lacrimal gland, primary bronchio-alveolar lung adenocarcinoma, and splenomegaly. high levels of the transgene rna were detected in mammary, harderian, and lung tumors. accumulation of cells of the myeloid lineages was found in enlarged spleens. this phenotype may represen ...	1989	2540427
human progesterone receptor binding to mouse mammary tumor virus deoxyribonucleic acid: dependence on hormone and nonreceptor nuclear factor(s).	using crude progesterone receptor preparations from t47d human breast cancer cells, we show by immunoprecipitation assay that receptor specifically and with high affinity recognizes the hormone response element (hre) of the mouse mammary tumor virus (mmtv). the use of crude preparations minimizes alterations of receptors or loss of associated factors that may occur during purification. specific binding was obtained at 1:1 molar ratios of receptor to dna, and hre sequences are recognized with an ...	1989	2540430
regulation of gene expression by glucocorticoids.		1989	2540703
expression of active hormone and dna-binding domains of the chicken progesterone receptor in e. coli.	bacterially-expressed fusion proteins containing the dna-(region c) or hormone-binding (region e) domains of the chicken progesterone receptor (cpr) fused to the c terminus of escherichia coli beta-galactosidase were analysed for the specificity of interaction with natural and synthetic hormone-responsive elements (hres) and progestins, respectively. the purified fusion protein containing the progestin-binding domain bound progesterone with an apparent kd of 1.0-1.5 nm and was specifically photo ...	1989	2540961
binding and transepithelial transport of immunoglobulins by intestinal m cells: demonstration using monoclonal iga antibodies against enteric viral proteins.	m cells of intestinal epithelia overlying lymphoid follicles endocytose luminal macromolecules and microorganisms and deliver them to underlying lymphoid tissue. the effect of luminal secretory iga antibodies on adherence and transepithelial transport of antigens and microorganisms by m cells is unknown. we have studied the interaction of monoclonal iga antibodies directed against specific enteric viruses, or the hapten trinitrophenyl (tnp), with m cells. to produce monospecific iga antibodies a ...	1989	2541137
shedding of virus-free mmtv gp52 by nonproducer mammary tumor cells: a source of tumor marker in the presence and absence of dexamethasone.	the envelope glycoprotein of the mouse mammary tumor virus (mmtv gp52), a useful plasma marker for mammary tumors in mice, was measured in extracellular medium by radioimmunoassay to quantitatively compare gp52 levels released by a c3h mmtv producer and its subcloned b9 nonproducer cell line. experiments analyzed levels of viral gp52 released from nonproducer cells both in the presence and absence of dexamethasone (dxs) to compare levels with those of producer cells and to assess quantitative ch ...	1989	2542180
positive and negative modification of dexamethasone-mediated mmtv gp52 release by progesterone pretreatment of tumor cells.	murine mammary tumor cells (c3h mm5mt/cl) were grown in charcoal-stripped serum to examine the effects of hormonal treatments on the expression and release of the mouse mammary tumor virus (mmtv) envelope glycoprotein (gp52). the ability of progesterone to modify extracellular levels of soluble and virion-associated mmtv gp52 was tested singly and as a pretreatment prior to dexamethasone (dxs) stimulation. single treatments with dxs or progesterone demonstrated that dxs was substantially more ef ...	1989	2542181
analysis of gag proteins from mouse mammary tumor virus.	structural proteins designated p10gag, p21gag, p8gag, p3gag, p27gag, and p14gag from the c3h strain of mouse mammary tumor virus (mmtv) were purified by reversed-phase high-pressure liquid chromatography. the n- and c-terminal amino acid sequences and amino acid composition of each protein were determined and compared with the amino acids encoded by the proviral dna sequences for the mmtv gag gene. the results show that each of the purified proteins is a proteolytic cleavage product derived from ...	1989	2542570
absence of mouse mammary tumor virus proviral amplification in chemically induced lymphomas of rf/j mice.	rf/j mice are susceptible to the induction of thymic lymphomas by the carcinogens 3-methylcholanthrene and n-methyl-n-nitrosourea. given the association of mouse mammary tumor virus (mmtv) with certain thymomas, we examined genomic dna from chemically induced lymphomas of rf/j mice for new mmtv proviruses. of 13 tissue culture lines derived from 3-methylcholanthrene-induced tumors, 5 had acquired new proviruses. mmtv amplification coincided with the appearance of viral mrnas and proteins. howeve ...	1989	2542628
glucocorticoids stimulate the release of a viral tumor marker (mmtv gp52) while inhibiting tumor cell growth.	the influence of glucocorticoid treatments on the release of mouse mammary tumor virus (mmtv) envelope antigen (gp52) has been studied in c3h mammary tumor cell cultures and compared to treatment-mediated effects on tumor cell growth. simultaneous assessment of extracellular viral antigen levels and tumor cell growth has indicated that both are coordinately affected by glucocorticoid treatment. while gp52 release is stimulated by treatment, this effect is accompanied by an inhibition of tumor ce ...	1989	2542692
dual function of a nuclear factor i binding site in mmtv transcription regulation.	using linker-scanning mutagenesis we had previously identified four elements within the mmtv ltr which are necessary for transcriptional stimulation by glucocorticoid hormones. two of them overlapped with regions to which the glucocorticoid receptor binds in vitro. the third element contained a nf-i binding site, and the fourth the tata box. here we show that mutations that abolish in vitro binding of nf-i had a negative effect also on the basal activity of the mmtv promoter of ltr-containing pl ...	1989	2542892
characterization of sequences related to the mouse mammary tumor virus that are specific to mcf-7 breast cancer cells.	mouse mammary tumour virus (mumtv) dna hybridized more strongly to two human ecori fragments (6.6 and 9.5 kilobases) in dna from the mcf-7 human breast cancer cell line than in dna from normal human placenta. seven recombinants (nmwv 1e1-7) containing these mumtv-related sequences were identified. hybridization of nmwv 1e probes to southern transfers of human dna suggested that these probes hybridize to multiple sequences in the human genome. the pattern obtained was very similar to that obtaine ...	1989	2544262
glucocorticoid responsiveness of mouse mammary tumor virus (mmtv) promoters in a down-transcription hepatoma tissue culture (htc) variant.	complement-mediated cytolysis of the mouse mammary tumor virus (mmtv)-infected rat hepatoma (htc) cell line, m1.54, resulted in recovery of a mutant derivative, designated cr5, in which the magnitude of both basal and dexamethasone-induced proviral mmtv rna expression was selectively reduced. variant cr5 cells were transfected with a plasmid containing the glucocorticoid-regulated mmtv promoter linked to the neomycin resistance gene (plnl). half-maximal resistance to g418 killing was glucocortic ...	1989	2545481
prolactin regulation of mouse mammary tumor virus (mmtv) expression in normal mouse mammary epithelium.	the hormonal regulation of mouse mammary tumor virus (mmtv) rna in normal mouse mammary epithelium was studied in an explant system. in tissue from parous mice, physiological concentrations of prolactin stimulated mmtv expression, while only pharmacological concentrations of cortisol were effective. regulation in explants from virgin mice was similar to that in parous animals except that the former were less sensitive to prolactin; this relative unresponsiveness may explain why uninduced tissue ...	1989	2545485
cooperative interactions between the grp78 enhancer and promoter elements in hamster fibroblasts.	a non-tissue-specific enhancer derived from the promoter of the rat 78-kda glucose-regulated protein (grp78)-coding gene was tested for its ability to stimulate the activity of its homologous promoter and two heterologous promoters (simian virus 40 and mouse mammary tumor virus). single and double copies of the enhancer were inserted at positions 5' and 3' of the cat-expression vectors under the direction of the above promoters. the recombinant plasmids were transfected into hamster fibroblast k ...	1989	2545535
phorbol ester-inducible t-cell-specific expression of variant mouse mammary tumor virus long terminal repeats.	acquired proviruses of mouse mammary tumor virus (mmtv) in t-cell leukemias of male gr mice have rearrangements in the u3 region of their long terminal repeats (ltr). in contrast to the endogenous nonrearranged mmtv proviruses, these mutated copies are highly expressed in leukemic t cells. to investigate whether the sequence alterations in the ltr are responsible for the high expression of rearranged mmtv proviruses, we made constructs in which normal and variant ltrs drive the bacterial reporte ...	1989	2545916
levels of viral glycoprotein provide a dose-dependent measure of tumor cell inhibition.	a chemosensitivity assay utilizing small replicate mm5mt/c1 c3h mammary tumor cell cultures was developed to determine whether changes in viral antigen expression and release into culture fluids could be utilized as an in vitro measure of chemotherapeutic drug effect. the 52,000 mw viral envelope glycoprotein (gp52) of the mouse mammary tumor virus (mmtv) was measured in culture fluids of control and drug-treated cultures while cell density was simultaneously determined by cell staining and od 6 ...	1989	2545986
highly inducible expression from vectors containing multiple gre's in cho cells overexpressing the glucocorticoid receptor.	a conditional glucocorticoid-responsive expression vector system is described for highly inducible expression of heterologous genes in mammalian cells. this host-vector system requires high level expression of the glucocorticoid receptor (gr) protein in the host cell and multiple copies of the receptor binding site within the expression vector. transfection and selection of chinese hamster ovary cells with expression vectors encoding the rat gr yielded cell lines which express functional recepto ...	1989	2546123
transgenic mouse model for human gastric carcinoma.	to understand the pathogenesis that may be induced by human adenovirus type 12 (ad12), we have generated transgenic mice carrying the ad12 early region 1 under control of the mouse mammary tumor virus long terminal repeat. eleven of 11 male founder mice, but only 2 of 12 females, died between 3 to 4 mo of age. death was associated with presence of tumors at or near the squamocolumnar junction of the stomach. microscopically, these multifocal tumors appeared to arise from hyperplastic epithelium ...	1989	2546160
the mechanism of camp-induced glucocorticoid receptor expression. correlation to cellular glucocorticoid response.	the mechanism of regulation of glucocorticoid receptor (gr) expression by camp was investigated in rat hepatoma cells (htc). incubation of htc cells with the camp-inducing agent, forskolin, caused a significant increase in the levels of both [3h]dexamethasone binding capacity and gr mrna by about 2- to 2.4-fold within 4 h. incubation of htc cells with the camp analogue, 8-bromo-camp, also increased the gr mrna level to a similar degree in a concentration-dependent manner. the increase in gr mrna ...	1989	2547771
use of a glucocorticoid-inducible promoter for expression of herpes simplex virus type 1 glycoprotein gc1, a cytotoxic protein in mammalian cells.	abundant expression of herpes simplex virus type 1 glycoprotein gc (gc1) in transfected mammalian cells has not previously been achieved, possibly because gc1 protein is toxic to cells. to approach this problem, the gc1 coding sequence was placed under the control of the weak but inducible glucocorticoid-responsive promoter from the mouse mammary tumor virus (mmtv) long terminal repeat (ltr). as controls to evaluate for gc1 cytotoxicity, the mmtv ltr promoter was used to express glycoprotein gd1 ...	1989	2548078
the mouse homolog of the hst/k-fgf gene is adjacent to int-2 and is activated by proviral insertion in some virally induced mammary tumors.	the fibroblast growth factor-related protooncogenes, int-2 and hst/k-fgf, are within 17 kilobase pairs of one another on mouse chromosome 7 and are in the same transcriptional orientation. approximately 70% of tumors induced in br6 mice by mouse mammary tumor virus have proviral insertions adjacent to the int-2 gene. we find that the murine homolog of the hst/k-fgf gene can also be transcriptionally activated by the insertion of mouse mammary tumor virus dna either upstream or downstream of the ...	1989	2548184
[the study on in vitro transformation by human papillomavirus type 16 e6/e7 region].	a nih3t3-derived cell clone (na7) in which human papillomavirus (hpv) 16 early region e6/e7 was inducible by dexamethasone (dxm) under the control of mouse mammary tumor virus long terminal repeat was established. a transforming function for hpv 16 e6/e7 region was analyzed by this established clone. northern blot hybridization demonstrated that the increased expression of pcna/cyclin and c-myc at the confluent state in accordance with the induced expression of e6/e7 region by dxm. although comp ...	1989	2548943
how steroid hormones work.	understanding how steroids work has led to improved comprehension of such derangements of hormonal regulation as testicular feminization. this knowledge has found practical application in the treatment of hormone-dependent cancers. gene therapy, albeit still too primitive to correct steroid-response defects, promises to be a future mainstay of management.	1989	2549083
thermodynamic stability and statistical significance of potential stem-loop structures situated at the frameshift sites of retroviruses.	rna stem-loop structures situated just 3' to the frameshift sites of the retroviral gag-pol or gag-pro and pro-pol regions may make important contributions to frame-shifting in retroviruses. in this study, the thermodynamic stability and statistical significance of such secondary structural features relative to others in the sequence have been assessed using a newly developed method that combines calculations of the lowest free energy of formation of rna secondary structures and the monte carlo ...	1989	2549508
independent glucocorticoid induction and repression of two contiguous responsive genes.	specific dna sequence elements which contain binding sites for the glucocorticoid receptor mediate the action of glucocorticoid hormones on gene transcription. in glucocorticoid-inducible genes, these glucocorticoid-responsive elements behave as hormone-inducible enhancers of transcription. we have taken advantage of the bovine papillomavirus (bpv) system to test the stringency of glucocorticoid regulation of transcription. bpv episomes were constructed to contain two hormone-regulated transcrip ...	1989	2550796
mutations in the hormone regulatory element of mouse mammary tumor virus differentially affect the response to progestins, androgens, and glucocorticoids.	transcription of the mouse mammary tumor virus dna is known to be induced by several steroid hormones. using chimeric mmtv plasmids containing mutations within the hormone regulatory element, we have previously studied the regions required for the glucocorticoid response in mouse fibroblasts. here we report the characterization of elements essential for the stimulation by progestins and androgens as compared with glucocorticoids. the same set of mutant plasmids was transfected into the human mam ...	1989	2550809
a quantitative comparison of dual control of a hormone response element by progestins and glucocorticoids in the same cell line.	progesterone receptor-containing t47d human breast cancer cells are responsive to progestins but fail to respond to other steroid hormones, in particular dexamethasone, because they have no measurable levels of receptors for estrogens, androgens, or glucocorticoids. to quantitatively study dual responsiveness of the mouse mammary tumor virus (mmtv) promoter to progestins and glucocorticoids, we have stably transfected t47d cells with a glucocorticoid receptor (gr) expression vector. a cloned der ...	1989	2550815
unique male mammary tumors developing in the inbred soft-furred field rats millardia meltada.	inbred lines of the soft-furred rat, millardia meltada, were studied with special reference to spontaneous male mammary tumors. adult males had the hyperplastic, pigmented inguinal mammary tissues and frequently developed bilateral mammary tumors. the tumors, no longer pigmented, were histologically well-differentiated adenocarcinomas associated with the myoepithelial cells and showed a variety of growth patterns depending on the stage of progression. they were transplantable to male, but not to ...	1989	2551171
spontaneous progression of hyperplastic outgrowths of the d1 lineage to mammary tumors: expression of mouse mammary tumor virus and cellular proto-oncogenes.	mammary cancer in mice is characterized by progression through defined stages of preneoplasia, with the most common preneoplastic stage being the hyperplastic alveolar nodule (han). we determined the relative levels of rna expression of various cellular proto-oncogenes and endogenous mouse mammary tumor virus genes in outgrowths and tumors of three sublines of the transplantable d1 han preneoplastic outgrowth line. the three sublines differed in relative tumor-producing capabilities. subline d1b ...	1989	2551332
expression of the int-1 and int-2 loci in endogenous mouse mammary tumor virus-induced mammary tumorigenesis in the c3hf mouse.	the int-1 locus appears to be involved in over 80% of c3h exogenous mouse mammary tumor virus (mmtv)-induced mouse mammary tumors, and the int-2 locus appears to be involved in approximately 10% of these tumors. analysis of 46 c3hf mammary tumors resulting from endogenous, rather than exogenous, mmtv infection revealed that only 41% expressed int-1 rna, while 2% expressed int-2 rna. our results suggest that in addition to the int-1 and int-2 loci, other loci may be involved in endogenous-mmtv-in ...	1989	2552179
caloric restriction perturbs the pituitary-ovarian axis and inhibits mouse mammary tumor virus production in a high-spontaneous-mammary-tumor-incidence mouse strain (c3h/shn).	dietary restriction (dr) retards aging and extends maximum life span. it is also known to decrease the incidence of hormone-dependent tumors. in the present investigation, we focussed primarily on the influence of dr on the pituitary-ovarian axis, and subsequently on gene expression of the mouse mammary tumor virus. f1 females from the mating of shn female and c3h male mice were used in this study, since these hybrids display a very high incidence of mouse mammary tumors. the mice weaned at 3 we ...	1989	2552231
host-mediated induction of tumor heterogeneity.		1989	2552891
no significant correlation between specific antibodies to mouse mammary tumour virus and human cancer.	to study the possible involvement of mouse mammary tumour virus (mmtv) related agent in human cancer we analysed 300 samples of human sera for the presence of antibodies to mmtv structural proteins. all sera were tested by immunoblotting to achieve high specificity. out of 300 sera, 22 reacted with transframe protein p30, 16 with the ribonucleoprotein p14, six with the envelope glycoprotein gp52 and three with the major core protein p27. reactivities to p30 and p14 were observed in sera from can ...	1989	2553093
reversible abrogation of il-3 dependence by an inducible h-ras oncogene.	immortalized, interleukin-3 (il-3)-dependent mouse mast cells (pb-3c) were transfected with a human activated c-h-ras gene under the transcriptional control of the mouse mammary tumor virus long terminal repeat. addition of increasing amounts of dexamethasone resulted in a concentration-dependent increase in expression of the h-ras oncogene. the elevation of p21 ras protein concentrations was paralleled by progressive growth of the transfectants in the absence of exogenous il-3, leading to compl ...	1989	2555182
glucocorticoid-regulated and constitutive trafficking of proteolytically processed cell surface-associated glycoproteins in wild type and variant rat hepatoma cells.	glucocorticoids regulate the trafficking of mouse mammary tumor virus (mmtv) glycoproteins to the cell surface in the rat hepatoma cell line m1.54, but not in the immunoselected sorting variant cr4. to compare the localization of mmtv glycoproteins to another proteolytically processed glycoprotein, both wild type m1.54 cells and variant cr4 cells were transfected with a human insulin receptor (hir) expression vector, prsvhir. the production of cell surface hir was monitored in dexamethasone-trea ...	1989	2558298