“…According to substrate specificity, sequence similarity, and domain organization, vertebrate MMPs are classified as collagenases (MMP‐1, ‐8, ‐13, ‐18), gelatinases ((MMP‐2, MMP‐9), stromelysins (MMP‐3, MMP‐10), matrilysins (MMP‐7, MMP‐26), membrane‐type MMPs (MMP‐14, ‐15, ‐16, ‐24, and MMP‐17, ‐25), and others (MMP‐12, ‐19, ‐20, ‐21, ‐23, ‐27, ‐28) . All MMPs contain a catalytic zinc‐binding motif, a linker region that links the catalytic domain region with the C‐terminal hemopexin (Hpx) domain, an N‐terminal signal sequence domain for secretion, a pro‐peptide region to maintain the latency for cell signaling . MMP‐13, also known as collagenase‐3, is secreted as an inactive pro‐form.…”