MMP9 and neoplasm: After CXCL8 binds to its receptor CXCR1/2, it can directly act on vascular endothelial cells or enhance the activity of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), promote the secretion of vascular endothelial growth factor (VEGF), induce the formation of new blood vessels and increase vascular permeability, which further provides nutritional support for the proliferation and migration of tumor cells (25).