Hypoxia not only supports the survival of neural and GSCs, which are inherently drug-resistant and possess tumorigenic potential, but it also stimulates the production of VEGF, leading to the formation of abnormal, leaky, and poorly organized tumor blood vessels, with an overexpression of transporters and receptors to meet the high metabolic demands of the rapidly proliferating tumor cells. The gene discussed is VEGFA; the disease is neoplasm.