CFTR and cystic fibrosis: In CF HIOs, a defective F508del-CFTR function (impaired Fsk-induced swelling) was rescued by treatment with the CFTR corrector, lumacaftor (VX-809) for 24 h, followed by acute potentiation with ivacaftor (VX-770) (Figure 1c,d), as expected from previous studies [14].