PARP1 and neoplasm: Radiosensitisation by PARP inhibitors is more pronounced in replicating cells;31,32 therefore, PARP inhibition may have greater potential to increase the therapeutic index of radiation when tumours are located in tissues with a low proportion of proliferating cells, such as the lung.33 Consistent with this, our recent study in non-tumour-bearing C57BL6 mice12 showed that PARP inhibition augmented radiation-induced toxicity in skin and oesophagus, two proliferative normal tissues.34,35