UCP2 and neoplasm: Although the authors state that their pathological analyses were presented only to provide a general understanding of the types of lesions during aging and were not intended to determine the cause of death, their valuable data showed a higher incidence of tumours in the UCP2−/− UCP3−/− (1.53 neoplasic lesions/mouse) compared to wild-type control (1.01 lesions/mouse), and a lower incidence in transgenic mice overexpressing UCP2 and UCP3 (0.64 lesions/mouse).