line T47D. steroid hormones in human breast cancer cell endogenous retrovirus genome by female Stimulation of expression of the human

Expressionofthe humanendogenousretrovirus genomeHERV-K,homologousto mousemammarytumorvirus, wasinvestigatedinculturedhumantumorcells. Inseveral cell lines, theHERV-Kgenomewasexpressedas an 8.8-kilobase poly(A)+ RNAwhich appeared to be a full-size transcript of this genome. In the humanbreast cancer cell line T47D,stimulation ofHERV-Kgenomeexpression by progesterone wasobserved afterestradiol treatment.Recently, human endogenous retrovirus genomes, somehomologousto mammaliantype B(1, 4, 12, 14, 23) orC(10,11, 16) retroviruses or unidentifiable retrovirus proviruses