CFTR and cystic fibrosis: Lumacaftor confers similar levels of F508del correction to low temperature as judged by Ussing chamber analysis (twofold increase in chloride transport) in an epithelial model widely utilized for studies of CFTR biogenesis and drug discovery (Fischer rat thyroid [FRT] cell model), typically used for CF drug screening applications, mechanistic studies, and expansion of FDA drug approvals in the United States (7, 8, 14, 15, 16, 17) (Fig. 2A).