Air liquid interface (ALI) cultures derived from human CF (ΔF508/ΔF508 CFTR) airway progenitor cells were treated with the secreted products in supernatants from PAO1, PAO1 ΔmexEFoprN, and PAO1 ΔmexEFoprNΔlasBΔrhlA cultures to test whether increased levels of elastase and rhamnolipids in the efflux pump mutant cause epithelial barrier damage. This evidence concerns the gene CFTR and cystic fibrosis.