GAPDH and neoplasm: Activity of HIFs further results in metabolic switch (affecting expression and function of glucose transporter 1 (GLUT1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), carbonic anhydrase 9 (CAIX), erythropoietin receptor (EPOR) and lactate-dehydrogenase 5 (LDH5), providing a selection benefit for the tumor cells.