CFTR and cystic fibrosis: Despite therapeutic effects observed in phase II clinical trials (Sermet-Gaudelus et al., 2010; Wilschanski et al., 2011), ataluren treatment only demonstrated a favorable trend, albeit not significant, to improve ppFEV1 of CF patients carrying a nonsense CFTR mutation in at least one allele in a phase III clinical trial (Kerem et al., 2014).