MMP-13, another member of the collagenase family, was recently discovered to be increased in alveolar macrophages and type II pneumocytes of COPD patients [28], and its expression was also found to correlate with shedding and aggregation in the bone marrow in non-small cell lung cancer patients, the effects of which are coincide with poorer survival rates [29]. Here, MMP13 is linked to chronic obstructive pulmonary disease.