CFTR and cystic fibrosis: Recently, Vertex Pharmaceuticals developed VX-809 (Lumacaftor), which increases the amount of F508del-CFTR in the plasma membrane of airway epithelial cells, and VX-770 (Ivacaftor), which increases the open probability of F508del-CFTR, to be given together to CF patients homozygous for the F508del CFTR mutation [9,11,12].