ACAN and intervertebral disk degenerative disorder: Matrix metalloproteinases (MMP) and ADAMTS (A Disintegrin and Metalloprotease domains, with thrombospondin motifs) are two major matrix-degrading enzymes involved in IDD; these enzymes promote the degradation of ECM molecules, such as aggrecan (ACAN) and collagen II (COL II) to further induce inflammation [19].