TP53 and breast cancer: As expected, these tumors failed to stain for p53 (Figure 5G) and Southern analyses confirmed Cre-mediated recombination of the conditional p53 allele in cultured mammary tumor cells derived from both the control (Ctipco/+/p53co/+/Wapcre/+) and experimental (Ctipco/−/p53co/+/Wapcre/+) mice (data not shown).