CDH1 and breast cancer: Though the mammary tumor incidence of p18mt mice in the Balb/c-B6 mixed background was lower when compared to the Balb/c background, as we previously reported 15, p18mt mammary tumors in a Balb/c-B6 mixed background were also E-cad positive, well-differentiated mammary tumors (Table 2, Figure 1, Figure 4, and data not shown).