CFTR and cystic fibrosis: The occurrence of CF disease in the human population is largely caused by deletion of Phe508 (F508) in the cystic fibrosis transmembrane conductance regulator (CFTR) protein (ΔF508-CFTR or ΔF508), leading to its retention in the endoplasmic reticulum (ER) and subsequent degradation by ER-associated degradation (ERAD) [3], [17]–[19].