Llinàs et al31 observed decreased TGF-β1 mRNA expression in the peripheral lungs of patients with severe stable COPD compared with control nonsmoking subjects, and in agreement with our present data, Kokturk et al32 found no difference in TGF-β1 immunohistochemical expression in the bronchial biopsy samples from patients with stable COPD and control nonsmoking subjects. Here, TGFB1 is linked to chronic obstructive pulmonary disease.