VEGFA and neoplasm: By focusing on HIF signaling in the study of the tumor hypoxic microenvironment, it has been found that HIF directly induces an increase in VEGF levels in ECs [48], VEGF contains a hypoxia response element (HRE) that can be activated in response to reduced oxygen, causing hypoxic tissues and macrophages to express VEGF and stimulate angiogenesis to restore oxygen and nutrient supply to hypoxic regions.