Insertional Mutagenesis in Mouse Mammary Tumorigenesis

Over the past few years, several surprising discoveries have been made regarding cellular oncogenes which are activated in mouse mammary tumors. These genes provide a particularly good example of the theme of this volume: host cell oncogenes activated by insertion of proviral DNA. They belong especially to this group because most of them have been discovered by virtue of insertional activation, through the application of provirus tagging methods. Quite unexpectedly, what several mouse mammary tumor virus (MMTV) activated oncogenes have in common is that they appear to play key roles in early normal development. In this chapter, the properties of the genes, their products, and their role in embryogenesis will be reviewed (see also Nusse 1988a, b).