A population of murine hematopoietic progenitors expresses an endogenous retroviral gp70 linked to the Rmcf gene and associated with resistance to erythroleukemia

Abstract
Multiple copies of retroviral sequences are stably integrated in the genomes of many higher organisms, and are thus transmitted vertically to offspring via the germline (1). Most of these heritable viral genes are not expressed, and expression, when observed, is commonly limited to envelope (env) genes as demonstrated by the presence of cell surface and serum envelope glycoprotein (gp70) in mice. Studies of the mouse have shown that certain tissues such as the reproductive tract and lymphoid organs are common sites for the expression of endogenous env genes, suggesting that the transcription of at least some endogenous sequences is tissue specific. The transcription of endogenous viral genes is regulated by both cis and trans mechanisms (2-5) and their expression can be temporally linked to differentiation and development (6-8).