S100A4 and chronic obstructive pulmonary disease: In this cross-sectional study, large airway endobronchial biopsy (EBB) tissues from patients with asthma (14), COPD (22), current (CS) and ex-smokers (ES), and ACO (12) were immunohistochemically stained for EMT markers (E and N cadherin, vimentin, S100A4, and Collagen IV) and compared with 12 current smokers with normal lung function (NLFS) and 10 non-smoking healthy control (HC) subjects.