RB1 and prostate intraepithelial neoplasia: Consistent with the TRAMP model, a similar phenotype of prostate cancer with neuroendocrine differentiation was also observed in the compound knockout mice with prostate-specific deficiency in p53 and Rb, although either p53 deletion or Rb loss alone only resulted in prostatic intraepithelial neoplasia (PIN) in aged mice [67].