PARP1 and breast cancer: In vitro studies showed that a sporadic breast cancer cell, UACC3199, carrying a hypermethylated BRCA1 promoter, conferred a similar degree of sensitivity to the poly(ADP-ribose) polymerase (PARP) inhibitor, olaparib, as did the mutated BRCA1 breast cancer cells, MDA-MB-436 and HCC1937, and a combination treatment with carboplatin was more effective than either drug alone [35].