“…To directly test the importance of erbB-2 in mammary tumorigenesis, transgenic mice carrying an activated form of the erbB-2/neu oncogene under the transcriptional control of the mouse mammary tumor virus long terminal repeat were derived. Mammary epithelial speci®c-expression of a constitutively active ErbB-2 or a similarly altered human erbB-2 in the mammary epithelium of transgenic mice (Bouchard et al, 1989;Guy et al, 1996;Luchini et al, 1992;Muller et al, 1988;Stocklin et al, 1993) results in the rapid induction of mammary tumors that histologically resemble human comedocarcinomas (Cardi and Muller, 1993). Interestingly, human comedo-carcinomas express elevated ErbB-2 levels (Morrison, 1994), have a higher proliferative rate and are clinically more severe than other ductal carcinoma in situ (Patchefsky et al, 1989).…”