HIF1A and neoplasm: Several studies have shown that tumor tissue hypoxia activates mainly Hypoxia-Inducible Factor-1 (HIF-1), which induces the expression of numerous angiogenic factors, such as Nitric Oxide Synthase (NOS), Vascular Endothelial Growth Factor (VEGF), Platelet-Derived Growth Factor (PDGF), Angiopoietin-2 (Ang 2), and others, promoting pathological angiogenesis (35, 36).