Matrix metalloproteinases: a multifunctional group of molecules.

The matrix metalloproteinases are a large group of zinc-containing proteases with a central role in the degradation of all types of extracellular matrix. Increased matrix degradation is a characteristic feature of several disease processes, most notably tumour invasion; it is now widely recognized that this group of proteases has a key role in facilitating invasion and metastasis. However, it is also becoming increasingly recognized that the matrix metalloproteinases are a multifunctional group of biologically important molecules with diverse roles in normal cell growth, differentiation, and cell regulation, and with involvement in the early stages of tumourigenesis. Some of these regulatory functions may be distinct from the matrix-degrading capabilities of this group of enzymes.