Figure 1: Glycolytic pathway and the role of HIF-1α in regulating glycolysis. Glucose was uptaken by increased expression of GLUT in hypoxia cancer cells. Through a series of enzyme reaction, glucose was finally metabolized into lactate and ATP, NAD+ was also regenerated by LDH-A for maintaining continuous glycolysis. Lactate was exhausted out of cancer cells by MCT4 and then uptaken by oxygenated cancer cells through MCT1. In the presence of oxygen, lactate is oxidized into pyruvate by LDH-B and pyruvate enters the tricarboxylic acid (TCA) cycle to produce ATP. HIF-1α was the main regulator of some enzymes expression in the glycolytic pathway, including GLUT-1, hexokinase, phosphofructokinase, pyruvate kinase, pyruvate dehydrogenase, LDH-A, and MCT.