New Drugs on the Horizon: Matrix Metalloproteinase Inhibitors.

Matrix metalloproteinases (MMPs) are a family of enzymes involved in a number of normal cellular processes, such as regulation of endometrial growth and menstruation, and abnormal processes, such as tumor growth, invasion, and metastasis. There are now 18 distinct enzymes that fall into three functional classifications based on their substrate target: collagenases which degrade fibrillar collagen; gelatinases which degrade denatured and basement membrane collagens, and stromelysins which degrade proteoglycans and glycoproteins. The MMPs can also be separated into five categories based on structural and functional similarities.