HIF1A and neoplasm: Angiogenesis is a key step in tumor growth, and the Warburg effect helps this process in several ways: (1) Lactate generated by glycolysis is released outside the cell through monocarboxylate transporters (MCTs), making the tumor microenvironment more acidic, activating HIF-1α in endothelial cells, inducing the expression of VEGF, and promoting angiogenesis (Végran et al., 2011).