siRNA -mediated knockdown of either p16INK4a or p15INK4b reduces the level of senescent cells, suggesting that, the p15INK4b-p16INK4a-pRb-E2F1 pathway (Table 1) regulates androgen-mediated cellular senescence in PCa cells [86, 90]. This evidence concerns the gene CDKN2B and posterior cortical atrophy.