The cytotoxic potential of arsenite was evaluated after treatment with NaAsO2 in the presence or absence of IR on UWB1.289 (BRCA1-null ovarian cancer cell line; BRCA1-deficient) and UWB1.289 + BRCA1 (BRCA1-wild-type, BRCA1-proficient) cells to define appropriate incubation conditions. Here, BRCA1 is linked to ovarian cancer.