Ferret and human ΔF508-CFTR lack significant apical surface CFTR in human CF polarized airway cells. Polarized human CF airway epithelial cells (CuFi) grown on Millicell membrane inserts were infected with human and ferret HA-tagged WT- and ΔF508-CFTR adenoviral vectors. At 48 h post-infection, the cells were brought to 4 °C, and a mouse anti-HA antibody was applied for 1 h to stain the surface HA-tagged CFTR (red). The unbound antibody was removed, and the cells were then fixed and permeabilized. Total CFTR (green) was stained using rat anti-CFTR (3G11) and rat anti-HA antibodies. The tight junctions (white) were stained using a rabbit anti-ZO-1 antibody. The membranes were excised and mounted with VectaShield containing DAPI (blue). Confocal immunofluorescent images of ferret and human WT-CFTR and ΔF508-CFTR are shown in the XY, XZ, and YZ planes with the single anti-HA channel shown to the right of the merged color images. The dotted lines represent the location of the Millicell membrane. Scale bars represent 10 μm.