Mice deficient in HNE or MMP-12 demonstrate decreased airspace enlargement and inflammatory cell infiltration after long-term exposure to cigarette smoke [11,12], COPD patients demonstrate increased activity of HNE and MMP's, including MMP-1 and 9, in their lungs [13-15], and mice which over-express MMP-1 develop adult onset emphysema [16]. The gene discussed is MMP12; the disease is chronic obstructive pulmonary disease.