Since in human breast cancer, Kras genetic alterations frequently co‐occur with TP53 genetic alterations (Fig. S1A), we crossed the MMTV‐rtTA TetO‐KrasG12D mouse with the Krt14‐Cre mT/mG Trp53f/f (Trp53 KO) mouse. The gene discussed is KRAS; the disease is breast carcinoma.