GAPDH and neoplasm: The authors successfullymeasured five different enzymes, including glucose-6-phosphate dehydrogenase (G6PD)in the pentose phosphate pathway (PPP), glyceraldehyde 3-phosphate dehydrogenase(GAPDH) in glycolysis, lactate dehydrogenase (LDH) in lactate fermentation, andisocitrate dehydrogenase (IDH) and succinate dehydrogenase (SDH) in thetricarboxylic acid (TCA) cycle, to evaluate the metabolic profile of single cells inintact tissues from healthy and tumor colon tissues [16].