TP53 and breast cancer: Comparing our mammary tumors to 13 other mouse models of breast cancer [20], most (4/6) Pten∆f:p53R270H spindle tumors clustered with other models of spindle tumors including certain p53-deficient, Brac1/p53-deficient and 7,12-dimethylbenzanthracene (DMBA)-induced mammary tumors (Fig. 4a).