We found that Grp78 expression was increased in G551D-CFTR expressing cells, suggesting that calumenin is likely involved in the maturation of CFTR within the ER, that G551D-CFTR may follow a specific maturation and trafficking pathway and that UPR may be triggered in CF independently of the retention of G551D-CFTR in the ER. Here, CFTR is linked to cystic fibrosis.