CFTR and cystic fibrosis: Further, we recently showed that ETI improves F508del-CFTR function to levels of 40%–50% of normal CFTR activity in the airways and intestine, and increases lung ventilation and improves mucus plugging and other morphological changes in the lungs of patients with CF with one or two F508del alleles (Graeber et al., 2022a; Graeber et al., 2022b).