Western blotting and immunohistochemical (fluorescence) staining analyses were performed as described previously18 (link),31 (link) with the following primary antibodies: actin monoclonal (1:5000 dilution; Sigma–Aldrich), FITC-conjugated anti-goat IgG, rhodamine-conjugated anti-rabbit IgG, alkaline phosphatase-conjugated anti-rabbit IgG (Jackson ImmunoResearch Laboratories), AhR and CC10 goat polyclonal antibodies (Santa Cruz Biotechnology), Notch1 and Hes5 rabbit polyclonal antibodies (cell signaling technology), AhR monoclonal antibody (Enzo life Sciences), and GFP rabbit polyclonal antibody (Abcam). Percentages of CC10 and Notch1 or HES5 double-positive cells in total airway cells were counted on 3–6 random fields from three animals.