Studies in other disorders such as tumor, atherosclerosis and many inflammatory diseases indicate that extracellular matrix degradation should be prerequisite for the migration of mononuclear cells and other cells in the tissue, and the ability of MMP-9 to degrade components of the extracellular matrix and to regulate the activity of a number of soluble proteins confers an important role in various physiological and pathological processes [16]. The gene discussed is MMP9; the disease is atherosclerosis.