Recently published data indicated that MMP9 by proteolytic inactivation of key T-cell chemoattractant CXC receptor 3 ligands, including CXCL9, CXCL10, and CXCL11, impaired the trafficking of tumor-infiltrating lymphocytes into the tumor microenvironment, an effective immune escape mechanism for many tumors. This evidence concerns the gene MMP9 and neoplasm.