TGFB1 and cystic fibrosis: Interestingly, we found that the highest local TGF-β1 concentrations in sputum were associated with intermediate FEV1 values (40–80% predicted) of CF patients over 5 years (p = 0.01), whereas for patients with both high (> 80% predicted) or low (< 40% predicted) FEV1 values over 5 years, the TGF-β1 concentrations were significantly lower.