TGFB1 and pulmonary fibrosis: In the present study, we revealed that CB1R-selective agonist ACPA substantially suppressed ECM production both in the lung tissues of mice with pulmonary fibrosis and in TGF-β-challenged lung fibroblasts, indicating that CB1R activation downregulated TGF-β signaling mediated the expression of ECM proteins in pulmonary fibrosis.