PARP1 and breast cancer: PARP inhibitor, ABT-888 (benzimidazole-4-carboxamide) hardly affected MCF-7 and MDA231 cells (not shown), and potent PARP inhibitors efficiently eradicating BRCA mutated breast cancer cells did not similarly eradicate MCF-7 cells [13,14] and cancer cells not carrying BRCA mutations [43].