Third, we used these highly differentiated CF patient–derived nasal epithelial cultures to investigate the relationship between ivacaftor-dependent effects on F508del-CFTR chloride channel function and the viscosity of the native mucus layer on cultures grown under near-physiological ALI conditions using fluorescent recovery after photobleaching, as well as mucociliary transport (MCT) by tracking the movement of fluorescent beads via time-lapse imaging. The gene discussed is CFTR; the disease is cystic fibrosis.