UBE2N and breast cancer: 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.