Signal transduction in mammary tumorigenesis: a transgenic perspective

A number of genes have been implicated in breast cancer development, yet fe w have been demonstrated to play causative roles in mammary tumor formation . The advent of transgenic mouse and embryonic stem cell technologies now p ermits manipulation of the mouse genome in such a way as to temporally and spatially control a gene product's expression. Thus, the basic researcher n ow can directly assess the involvement of particular genes in tumorigenesis and disease progression and, in the process, to develop mouse models of hu man genetic disease. The utility of such technologies is emphasized in tran sgenic mice expressing genes thought to play important roles in the initiat ion and progression of mammary carcinomas. As these transgenic strains have been the subject of several reviews, here we focus on two mouse mammary tu mor models, Polyomavirus middle T antigen and the Neu/ErbB-2 receptor tyros ine kinase, which are most amenable to study specific signaling pathways in process of mammary tumorigenesis.