In bronchial epithelial cells from people with cystic fibrosis (CFBE), when basolateral glucose concentration was raised, the loss of the ability to secrete HCO3− via the cystic fibrosis transmembrane conductance regulator (CFTR) led to a decrease in ASL pH, a factor known to contribute to the pathophysiology of CF disease (22; Fig. 2B). This evidence concerns the gene CFTR and cystic fibrosis.