FIGURE 1. PARP1 context-dependent functions in cellular life and death. Poly(ADP-ribose) polymerase-1 (PARP1) is a DNA repair enzyme activated in cancer cells treated with DNA damaging agents, and pharmacological PARP1 inhibitors can be used to improve chemotherapy and radiotherapy efficacy. PARP1 inhibition may also have neuroprotective effects by decreasing parthanatos-induced neuronal death. However, the ambivalent role of PARP1 in organismal aging and cell death modalities should be considered in view of the possible side effects of long-term treatments with PARP1 inhibitors. PARP1, Poly(ADP-ribose) polymerase-1; PAR: Poly(ADP-ribose); AIF: apoptosis inducing factor.