The mammalian Matrix metalloproteinases (MMPs) degrade extracellular matrix in physiological and pathological processes. After cleavage of a single peptide domain of about 20 amino acids, the MMPs are secreted in latent forms. Upon activation, the N-terminal propeptide domain is cleaved to generate the active forms of MMP. MMP-9 (92 kDa type IV collagenase, Gelatinase-B) contains the basic structure of propeptide, catalytic, and hemopexin domains. It is an important proteinase in tissue remodeling.