Sputum from 14 patients with inpatient CF exacerbation (average forced expiratory volume 1 second (FEV1)  = 39% (+/−24.1); 56%: delta F508 homozygotes, 22%: delta F508 heterozygotes, 22%:other genotype) were collected and analyzed for both MMP-9 and Ac-PGP peptides. Here, MMP9 is linked to cystic fibrosis.