CFTR and cystic fibrosis: A majority of CF patients has a deletion of a phenylalanine residue at position 508, resulting in an F508del-CFTR protein.25 The clinical importance of this mutation becomes evident because it accounts for 90% of patients diagnosed with CF.26 This mutation results in a misfolded channel retaining in the ER in an immature state and are rapidly degraded by a process involving the ubiquitin-dependent proteasomal system.24 Thus very little of this protein can reach the cellular membrane, resulting in the loss of function phenotype.