The five proposed mechanism-of-action-based biomarkers were: (1) BRCA1/BRCA2 germline mutation; (2) a 7-gene DNA-repair deficiency expression signature (PARPi-7) that predicts breast cancer cell line sensitivity to the PARP inhibitor olaparib; 34 (3) a 77-gene BRCA1ness expression signature;40, 41 (4) the CIN70 chromosomal instability expression signature;42, 43 and (5) PARP1 protein levels, the target of veliparib. Here, PARP1 is linked to breast cancer.