VX-445/VX-661 and 3C rescued 23.0% ± 1.4% and 19.5% ± 4.8% of WT CFTR function, respectively (mean ± SD), as determined by dividing the FSK response by the average non-CF nasal cell line response (i.e., 46.5 ± 5.0 μA/cm2) (Figure 1F and Supplemental Figure 2H). This evidence concerns the gene CFTR and cystic fibrosis.