The next immunofluorescence staining analysis showed that RAD51 nuclear foci (markers of HR repair capacity) were reduced and γH2AX nuclear foci (markers of DNA double‐strand breaks) were increased in two ovarian cancer cell lines (A2780 and OVCAR8) after treatment with MEnZn‐CuO NPs compared with controls (Figure 4b). The gene discussed is RAD51; the disease is ovarian cancer.