MMP9 and chronic obstructive pulmonary disease: In contrast to previous reports on case-control studies that showed an association of MMP1, MMP9 and MMP12 with COPD, emphysema, decreased levels of FEV1, and/or excess decline in FEV1 [12,14]., we found no indication whatsoever for a role of MMP1, MMP9 or MMP12 in the development of (mild to moderate) COPD or FEV1 decline in our prospective population studies.