PARP1 and neoplasm: In the presence of PARP inhibitors, dysfunctional PARP1 enzymes bind DNA and form PARP1‐DNA complexes and PARP inhibitors promote trapping of these PARP1‐DNA complexes that are toxic to the cell.102 A certain amount of functional PARP1 is critical to tumour responses to PARP inhibitors because PARP1 is required both as a substrate for PARP1 trapping and for the cytotoxicity of PARP inhibitors.