CFTR and cystic fibrosis: To test for functional conservation among human homologs of S. cerevisiae genes found to regulate Yor1-ΔF670 biogenesis, we used the human CF bronchial epithelial CFBE41o- (or CFBE) cell line with CFTRΔF508/ΔF508 genetic background with no detectable CFTR protein expression as a model [47].