The anti-tumor activities of PARP inhibitors occur through multiple mechanisms, including (1) trapping the enzyme to the single-strand DNA breaks (SSBs) by preventing the utilization of nicotinamide adenine dinucleotide (NAD), and (2) inhibiting poly ADP-ribosylation (PARylation) and binding of PARP to DNA (15). The gene discussed is PARP1; the disease is neoplasm.