For example, nonmitochondrial SIRT1, SIRT2 and SIRT6 are expressed at higher levels,429–431 while mitochondrial SIRT3-5 are expressed at lower levels in HCC tissues compared with normal liver or surrounding tumor tissue.432–434 SIRTs could be prognostic markers for patients with HCC. The gene discussed is SIRT2; the disease is hepatocellular carcinoma.