H2AX and posterior cortical atrophy: To determine whether RRM2 regulates the DNA damage response (DDR) in PCa, we treated RRM2-overexpressing or RRM2-depleted prostate cancer cells with 10 nM Docetaxel (DTX) for 30 min and performed γ-H2AX staining, which is a widely used marker for DNA double-strand breaks (DSBs), at 30 min or 24 h after DTX treatment.