CFTR and cystic fibrosis: Cystic fibrosis (CF) is caused by recessive mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a phosphorylation-regulated chloride/bicarbonate channel localized on the apical epithelial surface of the pulmonary and gastrointestinal tracts, pancreatic ducts, and the male reproductive ducts [1, 2].