Although treatment with PARP inhibitors can never reach the level or the persistence achieved through the genetic knockout of PARP-1/PARP-2 in lymphocytes, our data demonstrating a redundant role for PARP-1 and PARP-2 in the T-cell immune response and tumour suppression in T-cells may have implications for the use of non-selective inhibitors in human patients. The gene discussed is PARP1; the disease is neoplasm.