Together with the absence of intestinal tumors, the most striking phenotypic feature of the Apc+/1572T mouse model is undoubtedly represented by the highly penetrant incidence of multifocal mammary tumors among virgin females (100%) and males (30%), in sharp contrast with Apc+/Min and Apc+/1638N animals (1/6 and 0/14, respectively) (Table 1, Figure 3A–3D). The gene discussed is APC; the disease is breast cancer.