PKM and cancer: Pyruvate kinase isoform M2 (PKM2), one of the isoenzymes of pyruvate kinase (PK) (Yang and Lu, 2013), is a key glycolytic enzyme overexpressed in cancer cells (Luo and Semenza, 2012), which controls the terminal rate-limiting step of glycolysis by catalyzing the transform of a phosphate group from phosphoenolpyruvate (PEP) to adenosine diphosphate (ADP) (Hamanaka and Chandel, 2011).