GSK3B and chronic obstructive pulmonary disease: Immunohistochemical staining also indicated strong phospho-GSK3β-Ser9 staining in bronchial epithelium of smokers with and without COPD, although all bronchial epithelial cells in lung tissue stained positive for phospho-GSK3β-Ser9 and we did not detect clear differences compared with nonsmoking controls using this method (Fig. 1F).