In vitro experiments with CuFi1 and NuLi1 cell lines from human bronchial epithelium of a CF (CuFi1, CFTR ΔF508/ΔF508 mutant genotype) and a non‐CF subject, respectively, (spray‐dried naringin cosprayed with 5% leucine, 30 μM concentration). This evidence concerns the gene CFTR and cystic fibrosis.