MMP9 and cystic fibrosis: When the ratio of total or active MMP-9 to extracellular LTA4H levels/activity was determined, there was a clear and striking augmentation in the CC-CF children relative to non-CF controls and RSISP-CF patients (Fig. 4A; Supplementary Fig. 3A and B), rationalizing the clear separation in levels of PGP between the groups of children.