CDK4 and Familial prostate cancer: In this study, we aimed to estimate the contribution of these selected polymorphisms (CDK4 rs2069502, CDK6 rs2285332, CCND1 rs9344, p16INK4a rs11515, p15INK4b rs3217986, RB rs3092904) within the cyclin D-CDK4/6-INK4-RB pathway to prostate cancer risk.