PKM and glioma: Tumor glycolytic enzymes hexokinase 2 (HK2), 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3), pyruvate kinase M2 (PKM2), and lactate dehydrogenase 5 (LDH5) demonstrate increased activity in the glioma cells and supposed to be preferentially used by cancer cells.