RAD51 and neoplasm: Taken together, these data suggest that while a tumor cell less sensitive to SG may be proficient in activating HRR-mediated pathways, as evidenced by increased Rad51 expression and lower levels of dsDNA breaks, there is a threshold of SN-38-mediated damage above which cells are unable to maintain adequate DNA repair, resulting in increased dsDNA breaks and likely pushing cells towards apoptosis.