PKM and cancer: PFK-L forms clusters in human cancer cells and colocalizes with other rate-limiting enzymes in both glycolysis and gluconeogenesis, supporting the formation of multienzyme metabolic complexes for glucose metabolism, integrating PFK-L, FBPase1, the pyruvate kinase isoenzyme M2 (PKM2) and phosphoenolpyruvate carboxykinase 1 (PEPCK1), among others, and forming the “glycosome” (53).