During hypoxia of tumor cells, the upregulated hypoxia inducing factor (HIF)-1α forms a heterodimer with HIF-1β to become a transcription factor HIF-1 that activates pro-angiogenic genes such as vascular endothelial growth factor A (VEGFA), to promote angiogenesis for tumor growth and metastasis [77,78]. The gene discussed is HIF1A; the disease is neoplasm.