CFTR and cystic fibrosis: pH in phagolysosomes in alveolar mφs from CFTR-null mice was ∼2 pH units more alkaline than those from control mice and there was a defect in lysosomal acidification in CFTR-null alveolar mφs, with pH ∼ 6 in CF mφs vs. ∼4.5 in control mφs, which was proposed, by a delayed phagolysosomal fusion mechanism, accounting for the defect in acidification [71].