CFTR and cystic fibrosis: Cystic Fibrosis (CF), the most common severe autosomal recessive disease in Caucasians, is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene [1]–[3] which encodes a cAMP-regulated chloride (Cl−) channel expressed at the apical membrane of epithelial cells to control salt and water transport [4].