Results of gene expression of (fibronectin, vimentin, α-SMA, and Smad2/3) in MCR-5 revealed that cells treated with TGF-β1 only (10 ng/ml) expressed high levels of the targeted genes, proving the fact that TGF-β1 is a fibrogenic cytokine and a key player and regulator in the development and progression of pulmonary fibrosis by promoting the activation, proliferation, and migration of fibroblasts, ECM deposition and the transformation from fibroblasts to myofibroblasts84,85. The gene discussed is SMAD2; the disease is pulmonary fibrosis.