TP53 and breast carcinoma: Both, WapCre;Trp53flox and PyMT mice, which develop spontaneous mammary tumors of luminal origin24, were crossed to MB-proficient and -deficient mice to generate mouse models where marker (MB) and transforming event (middle T (MT) antigen or p53 knockout) co-occur in the same cellular context, thus, mimicking the situation of breast cancer patients.