STAT3 and pulmonary fibrosis: To further confirm the role of VDR activation on pulmonary fibrosis, we constructed a lentiviral vector (Lv-VDR) that expresses VDR and examined the effect of ectopic VDR overexpression on bleomycin-induced activation of JAK/STAT3 signaling pathway, ER stress, fibroblast proliferation, and differentiation into myofibroblasts in vivo.