HIF1A and neoplasm: This protein inhibits glioma stem cell differentiation by producing high levels of 2-hydroxyglutaric acid (2-HG), upregulates vascular endothelial growth factor (VEGF) to promote tumor microenvironment formation, and produces high levels of hypoxia-inducible factor-1α (HIF-1α) to promote glioma invasion, which ultimately leads to the development of glioma (Figure 1).