SIRT4 and neoplasm: In another report, Sirt4 overexpression in HepG2 cells correlated with reduced levels of cleaved caspase-3, thus reducing apoptotic cell death (anti-apoptotic effect) and increasing the survival and the cellular clone formation rate of tumor cells in response to different DNA-damaging conditions such as cisplatin, radiation, and UV irradiation, and Sirt4 loss sensitized cells to drug treatment (47) (Table 1).