Matrix metalloproteinase 7 (MMP-7), or matrilysin, is a secreted protease expressed by glandular and mucosal epithelial cells, keratinocytes, fibroblasts and macrophages. As with other MMPs it can act on the extracellular matrix and thereby regulate cell migration and tissue repair. In addition, MMP-7 has an important role in the maintenance of innate immunity in organs such as the lungs and intestines where it proteolytically activates anti-bacterial peptides such as pro-defensins. MMP-7 is also important for mediating proteolytic release of TNF from macrophages. Consistent with its role in innate immunity, MMP-7 is induced by microbial products and also, unexpectedly, by hypoxia.