MMP9 and neoplasm: Moreover, tumor cells secrete granulocyte colony-stimulating factor to induce the release of neutrophils from the bone marrow, which leads to an increase in neutrophils in the body, thereby stimulating the body to secrete matrix metalloproteinase-9 and vascular endothelial growth factor, which promote angiogenesis, degrade the matrix around the tumor, and inhibit lymphocyte-mediated cytolysis, thereby promoting malignancy proliferation and metastasis [21, 22].