TP53 and prostate intraepithelial neoplasia: Prostatic intraepithelial neoplasia (PIN) lesions were observed in B6.129S4-Trp53tm3.1Tyj/J mice that were homozygous (Trp53R270H/R270H) or heterozygous (Trp53R270H/+) for the Trp53 R270H mutation (Figure 1A), indicating that the p53 R270H mutation can drive CaP initiation in this setting.