PARP1 and cancer: We chose PARP-1 because (1) the many known PARP-1 inhibitors (PARPi) serve as positive controls and leads to optimize [12–15]; (2) PARPi are effective treatments for many cancers with defects in the Breast Cancer (BRCA) 1 and 2 genes [16, 17]; and (3) the PARP-1 catalytic domain has a well-characterized druggable pocket [18–20].