Thus, in this study, we investigated the role of ATR and CHK1 inhibition at the early stage of olaparib response in BRCA2MUT (PEO-1) and BRCAWT (OV-90 and SKOV-3) ovarian cancer cells and sought to further elucidate the mechanisms leading to ovarian cancer cell death. Here, CHEK1 is linked to ovarian cancer.