Basement membrane degeration is mediated by

They are zinc-dependent endopeptidases; other family members are adamalysins, serralysins, and astacin. The MMPs belong to a larger family of proteases known as the metzincin superfamily. Collectively they are capable of degrading all kinds of extracellular matrix proteins. They cleave cell surface receptors, release the apoptotic ligands (such as the FAS ligand), and inactivate chemokines/cytokines. MMPs also play a major role on cell proliferation, migration (adhesion/ dispersion), differentiation, angiogenesis, apoptosis and host defense. The MMPs play an impoant role in tissue remodeling associated with morphogenesis, angiogenesis, tissue repair, cirrhosis, ahritis, and metastasis. MMP-2 and MMP-9 are thought to be impoant in cancer metastasis. MMP-1 is involved in rheumatoid ahritis, osteoahritis and aoic aneurysm. Excess MMPs degrade the structural proteins of the aoic wall. The MMPs are inhibited by specific endogenous tissue inhibitor of metalloproteinases (TIMPs), which comprise a family of four protease inhibitors: TIMP-1, TIMP-2, TIMP-3, and TIMP-4.Ref: DM Vasudevan, page no: 548