Similar defects in fork recovery were observed in a BRCA1-deficient ovarian cancer cell line, UWB1.289 (UW, for simplicity), (Supplementary Figure S1B) and in BRCA1-depleted MDA-MB-231 breast cancer cells upon loss of either RAD18 or UBC13 (Supplementary Figure S1C, D), indicating that the observed phenotype is not cell type specific. Here, BRCA1 is linked to ovarian cancer.