Irradiation-mediated p53LOH in p53H/+;ErbB2 mammary tumors was associated with significant stabilization of mutp53 protein in vivo (Fig. 3a, and Supplementary Fig. 2b) and in cell lines generated from mammary tumors that underwent p53LOH in vivo (Fig. 2d, lanes 9–11 and Supplementary Fig. 2a). This evidence concerns the gene ERBB2 and breast cancer.