The newest study by Mahmood et al. demonstrated that TGF-β1 expression was generally higher in COPD subjects throughout the airway wall, while p-Smad2/3 expression was associated with smoking, especially in current smoking COPD; in addition, p-Smad was related to airflow obstruction and S100A4 expression [9]. This evidence concerns the gene TGFB1 and chronic obstructive pulmonary disease.