PDK1 and cholangiocarcinoma: SIRT3 down-regulates HIF1α and pyruvate dehydrogenase kinase 1 (PDK1) in cholangiocarcinoma (49), and suppresses the Warburg effect also by the activation of pyruvate dehydrogenase complex (PDC) and the indirect inhibition of the tumor specific isoenzyme hexokinase II (HK II) (11).