CFTR and cystic fibrosis: Although this effect of chronic ivacaftor exposure may have implications for clinical outcomes in patients with CF, data on a potential role of specific cell culture conditions on the effects of chronic ivacaftor treatment on restoration of F508del-CFTR–mediated chloride secretion are limited, and downstream effects on abnormal viscoelastic properties of airway mucus and impaired mucociliary clearance characteristic of CF have not been studied.