These results are consistent with previous studies by van Goor and colleagues showing that chronic exposure with VX-809 followed by acute addition of VX-770 restored CFTR-mediated chloride transport across human bronchial epithelial cultures from F508del homozygous patients to approximately 25% of that measured in non-CF human bronchial epithelial cells and that this increase in Cl− transport translated into an increase in the ASL height14. The gene discussed is CFTR; the disease is cystic fibrosis.