Intriguingly, we observed that R26hARL/wt:p16L/L:PB-Cre4 compound mice developed PIN in all prostatic lobes (Fig 2B1-3 versus Fig 1C1-2), suggesting that the atypical lesions observed in the p16 knockouts were indeed precursor lesions. This evidence concerns the gene CDKN2A and prostate intraepithelial neoplasia.