BRCA1 and neoplasm: In keeping with low U-ssDNA accumulation in BRCA1-deficient cells, AP sites were also not significantly increased in cisplatin or HU-treated BRCA1-deficient cells (BRCA1 targeted by two different siRNAs) (Fig. 3f, g) or in BRCA1 mutant tumor line UWB1.289 (Fig. 3h).