As such, these tumors broadly resembled the basal-like carcinomas that develop following mammary-specific co-inactivation of Brca1 and p53 [30–32], but contrasted starkly with the sarcomatous or spindle-like breast tumors of the control p53-mutant (Ctip+/+,co/+/p53co/+,co/co/Wapcre/+) mice (data not shown). This evidence concerns the gene TP53 and breast neoplasm.