MMP13 and cystic fibrosis: Importantly, all of the other biomarkers analyzed (MMP-1, MMP-2, MMP-13, TIMP-2, HA, PIIIP) were unaltered between CF patients with PEx and those without, thereby indicating that ECM markers are not generally up-regulated in CF patients with pulmonary exacerbation and declined lung function, but rather occurs selectively on the level of individual markers.