Matrix metalloproteinases are a family of zinc and calciumdependent endopeptidases, which degrade extracellular matrix proteins. MMP-9 is secreted as a 92kDa zymogen. Cleavage of pro-MMP-9 results in the active enzyme with a molecular weight of ~82kDa. MMP-9 has a gelatinbinding domain consisting of three fibronectin type II units, a catalytic domain containing the zinc-binding site, a proline-rich type V collagen-homologous domain and a hemopexin-like domain. MMP9 is produced by monocytes, macrophages, neutrophils, keratinocytes, fibroblasts, osteoclasts and endothelial cells, and is involved in inflammatory responses, tissue remodelling, wound healing, tumour growth and metastasis.
