Pyruvate kinase type M2 or PKM2 is present in embryonic, adult stem cells. It is also expressed by many tumor cells. The alterations to metabolism by PKM2 increases ATP resources, stimulates macromolecular biosynthesis and redox control. Pyruvate kinase catalyses the ATP-generating step of glycolysis in which phosphoenolpyruvate (PEP) is converted to pyruvate. This is a rate-limiting step. It decreases the glycolysis activity and allows carbohydrate metabolites to enter other pathways, like hexosamine pathway, Uridine diphosphate glucose–glucose synthesis, glycerol synthesis and Pentose phosphate pathway or PPP. It helps in generating macromolecule precursors, that are necessary to support cell proliferation, and reducing equivalents such as NADPH. It has been observed in some studies that MYC promotes expression of PKM2 over PKM1 by modulating exon splicing.
A key molecule produced as a result of the oxidative PPP by PKM2 is NADPH. NADPH functions as a cofactor and provides reducing power in many enzymatic  reactions that are crucial for macromolecular biosynthesis. Another mechanism by which NADPH is produced in mammalian cells is the reaction converting isocitrate to α-ketoglutarate (αKG), which is catalysed by NADP-dependent isocitrate dehydrogenase 1 (IDH1) and IDH2 and have been found linked to tumorigenesis in glioblastoma and acute myeloid leukemia. They are also found to interact with arginine residues required for isocitrate binding in the active site of the proteins of IDH1 and IDH2.