Wild-type and KO tracheal epithelial cells exhibit comparable in vitro differentiation. (A–D) Wild-type (A, C) and KO (B, D) tracheal epithelial cell cultures were grown at an air–liquid interface (ALI) that promotes differentiation closely resembling a normal in vivo epithelium. Differentiated ALI cultures were stained for K14 (green; A, B), acetylated tubulin (ACT; red, A, B), and CCSP (red; C, D) to assess differentiation. (E–G) K14-positive basal cells (E), ACT reactive ciliated cells (F), and CCSP-expressing Clara cells (G) all exhibited comparable abundance between wild-type and knockout samples as a function of total ALI surface area. Four ALI cultures per genotype were analysed; error bars represent standard error of the mean. All samples were also stained with DAPI nuclear dye (blue; A–D). Scale bars are 100 µm (A–D)