ANGPT1 and neoplasm: Under the stimulation of hypoxia, HIF-1 generated by tumor cells facilitates the secretion of various proangiogenic factors, such as fibroblast growth factor (FGF), platelet derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and angiopoietin-1 (Ang-1), thus promoting the proliferation, migration, and transformation of vascular endothelial cells [4].