Tumor internal environment can induce HIF-1 activating cells, to release a large amount of vascular endothelial growth factor-A (VEGF-A), vascular endothelial growth factor-2 (VEGF-2), fibroblast growth factor-2, and stromal cell-derived factor-1α/β (SDF-1α/β). The gene discussed is HIF1A; the disease is neoplasm.