In order to simulate the situation in the BRCA1-deficient ovarian tumours carrying lower OGG1 amounts, we made use primarily of the human ovarian carcinoma cell line A2780 (ECACC 93112519), which was treated with various combinations of siRNAs (Supplementary Figure S1) and subsequently with olaparib. Here, BRCA1 is linked to ovarian neoplasm.