PARP1 and cancer: Despite evidence indicating that PARP1 inhibition interferes with oncogene expression in malignant cells,31 PARP1 inhibitors have been mainly examined for their role in reinforcing the activity of DNA-damaging agents or in BRCA mutant cancer cells105 in which double-strand DNA break repair is impaired.106,107 PARP1 inhibition preventing DNA repair also interferes with the repair of damaged DNA in p53 mutant cancer cells,108,109 and promotes cell death in PTEN phosphatase mutant cells with an uncontrolled Akt kinase activity.110