However, it can be induced by endogenous ligand versican of TLR2 secreted by tumor cells in close contact with tumor cells, and its own TLR2 is activated to induce MT1-MMP expression, accompanied by up-regulated expression of MMP-9, and the magnitude of expression is directly proportional to the malignancy of glioma (134–136). This evidence concerns the gene VCAN and central nervous system cancer.