Background. Cystic fibrosis (CF) is a severe hereditary disease caused by mutations that abolish the function of a membrane protein (named CFTR) needed to transport chloride ions. The most frequent mutation in CF patients is the deletion of phenylalanine 508 (F508del), causing misfolding and premature degradation of the mutant protein. The trafficking defect can be rescued by molecules called correctors, however, the efficacy of known compounds is reduced. By studying proteins that interact with CFTR we identified the ubiquitin ligase RNF5 as a protein of particular interest, since its inhibition can lead to mutant CFTR rescue both in vitro and in vivo using animal models.