HIF1A and cancer: Another variant of metabolic symbiosis was revealed by the immunohistochemical examination of colorectal carcinoma: cancer cells expressed transporters (GLUT1, MCT1) and enzymes (LDH5, HIF1) associated with anaerobic metabolism, whereas CAFs lacked these proteins and expressed transporters (MCT1, MCT2) and enzymes (LDH1) involved in lactate uptake and oxidation [141].