Matrix metalloproteinase 9 (MMP9) is a gelatinase enzyme, which catalyzes the degradation of gelatin and collagen and is preferentially inhibited by tissue inhibitor of metalloproteinases 1 (TIMP-1). The MMP9 protein is a zinc-dependent protease which is responsible for degradation of extracellular matrix components. It also participates in the pathogenesis of cancers. MMP9 is associated with various disorders, such as cystic fibrosis, acute lung injury, asthma as well as respiratory syncytial virus infection both in vitro and in vivo. MMP-9 is involved in a variety of autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and multiple sclerosis and be regarded as a potential therapeutic target. Mutation of MMP-9 is associated with lumbar-disc herniation (LDH) and metaphyseal anadysplasia (MAD).
