Alveolar wall liquid (AWL) secretion prevents acute lung injury (ALI), a disease of lung alveoli, by generating liquid flow on the apical surface of the alveolar epithelium and transporting injurious particles and bacteria from alveoli. This physiological process is mediated by the alveolar epithelial cystic fibrosis transmembrane conductance regulator (CFTR) ion channel. Although both alveolar type 1 (AT1) and 2 (AT2) epithelial cells express CFTR, the cell type that drives AWL secretion is unclear. In vitro studies of cultured cells suggest AT2 cells are the source of AWL secretion. However, AT1 cells may be the driver in vivo on account of their extensive lung surface area. To study the role of live AT1 cell CFTR in AWL secretion, we employ live lung imaging of mouse lungs from a novel cell-specific fluorescent CFTR knockout mouse model.