The higher expression of cell cycle inhibitors p21WAF1/CIP1, p27KIP1 and lower expression of cyclin-dependent kinases CDK1, CDK4, cyclin E1 and cyclin B1 in PCa cells also proves the combinatorial effect of RES and DTX, which stop the transition of cells from G1/S and G2/M phase. This evidence concerns the gene CDK4 and posterior cortical atrophy.