BRCA1 and cancer: To search for mechanisms of PARPi resistance in cancers specifically with BRCT domain-disrupting mutations, we initially characterized the effects of the PARPi rucaparib on SNU-251 cells, an endometrioid ovarian cancer cell line that carries a BRCA1 5564 G > A (c.5445 G > A) non-sense mutation in exon 23 41.