Although genetic abnormalities in prostate cancer have been reported for other important cell cycle regulators such as phosphatase and tensin homologue (Majumder and Sellers, 2005), the retinoblastoma tumour suppressor protein (RB), and p53 (MacGrogan and Bookstein, 1997), perturbations in cyclin D1 appear to be less common. Here, RB1 is linked to Familial prostate cancer.