CFTR and cystic fibrosis: Epithelial cells expressing the cystic fibrosis transmembrane conductance regulator (CFTR) gene with the Phe508del mutation—the most common mutation in patients with CF—show hyper-activity of p38MAPK in response to Pa [22–24], which may be a result of endoplasmic reticulum stress and therefore sensitisation of the cells to microbial stimuli [25].