Matrix metalloproteinases (MMPs) (1,2) comprise a family of over 20 matrix degrading enzymes believed to be essential for normal development and physiologic tissue remodeling and repair. Abnormal expression of metalloproteinases has been implicated in many destructive processes, including tumor cell invasion and angiogenesis, arthritis, atherosclerosis, and arterial aneurysms. With respect to lung disease, MMPs have been associated with chronic obstructive pulmonary disease (COPD), acute lung injury, pulmonary fibrosis, and asthma. The role of MMPs in causation of pulmonary emphysema has been supported by transgenic mice overexpressing MMP-1 (3) and gene targeted mice lacking MMP-12 (4).