Decreased CFTR expression (KE1) in airway epithelium has been observed in cystic fibrosis and after hypoxia and cigarette smoke exposure, resulting in reduced Cl− transport and, ultimately, reduced ASL depth (Alexander et al., 2012; Clunes et al., 2012; Rasmussen et al., 2014; Woodworth, 2015; Raju et al., 2016). The gene discussed is CFTR; the disease is cystic fibrosis.