RAD51 and cancer: Four cell lines (OE19, FLO-1, MCF7 and HCT116) representing three different cancers were treated with RAD51 inhibitor, alone or in the presence of a DNA breaking agent, either camptothecin (CPT; a known DNA breaking agent [33]), 5-fluorouracil (5-FU) or paclitaxel (PTX) as indicated in Figure 2C. Treatment of cancer cell lines (OE19, FLO-1, HCT116 and MCF7) with all these genotoxic agents caused an increase in DNA breaks, whereas addition of RAD51 inhibitor led to reduction in DNA damage caused by these agents (Figure 2D).