Matrix metalloproteinases (MMPs) are a family of endoproteases that require zinc and calcium for expressing catalytic activity. These enzymes play a central role in the maintenance and remodeling of the extracellular matrix. Elevated expression of their activity, caused either by up-regulation of their expression or down-regulation of their cognate inhibitors, has been implicated in various degenerative disorders, including arthritis, cardiovascular disease, skeletal growth-plate disorders, and cancer metastasis. MMP-3 degrades fibronectin, laminin, collagens III, IV, and X, and cartilage proteoglycans. Recombinant human MMP-3 is a 42.8 kDa protein containing the entire catalytic N-terminal domain and the C-terminal domain (378 amino acids).