CFTR and cystic fibrosis: An interesting question in CF is whether the new class of drugs designed to facilitate folding/biogenesis of CFTR, such as Lumacaftor, influence stress in the ER.61, 62 Lumacaftor is a chaperone type drug that is designed to aid folding in the ER to enhance release of mutant CFTR to the cell surface where it has partial ion channel function.