High levels of proteinase-3 (PR3) [39] and cathepsins G [40], B, L and S [29] are also present in CF bronchoalveolar lavage fluid, as well as macrophage- and neutrophil-derived metalloelastases (MMP-8, MMP-9) [41] and elastolytic proteases expressed by P. aeruginosa [15]. Here, MMP9 is linked to cystic fibrosis.