MMP9 and neoplasm: Among the factors affecting tumor angiogenesis, the most critical one is vascular endothelial growth factor (VEGF), and HIF-1α affects tumor cell glucose metabolism by regulating VEGF, hepatocyte growth factor (HGF), and vascular cell adhesion molecule 1 (VCAM1) [18], whereas HIF-1α increases the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9.