CFTR and cystic fibrosis: Cystic Fibrosis is caused by a mutation in the gene encodingtheCystic Fibrosis transmembrane conductance regulator (CFTR) protein,which transports chloride and bicarbonate ions to the airway surfaceliquid.17 The transport of pH buffer bicarbonatehas garnered much interest because acidified airway surface liquidhas been shown to reduce the activity of antimicrobial peptides andincrease the risk of airway infection.5 However, whether the airway surface liquid is more acidic in individualswith Cystic Fibrosis is still debated.13,18