CCND1 and posterior cortical atrophy: To elucidate the possible alterations in cell cycle and apoptosis following IR that contribute to radioresistance of PCaRR, we analyzed the expression of key proteins, namely cyclin D1, a mediator of PCa radioresistance [42], pro-apoptotic BAX, anti-apoptotic isoforms of c-FLIP and apoptotic downstream mediator caspase 3.