HIF1A and neoplasm: The severer the environmental hypoxia is, the more stable HIF‐1α will be, thereby helping enhance stability and proliferation capacity of tumor cells.19 Some studies have demonstrated that the stronger the expression of nuclear antigen in tumor cells is, the higher the level of HIF‐1α will be, the synthesis and secretion of HIF‐1α are promoted by tumor cells due to hypoxia, and the level is closely related to angiogenesis.20, 21