However, because we do not provide direct evidence of the mechanism by which TGF-β1 increases tissue fibrosis in MIAs, and we examined only a limited number of patients, further studies will be needed to more precisely define the role played by tumor-derived TGF-β1 in determining the invasiveness of adenocarcinoma of the lung. The gene discussed is TGFB1; the disease is lung adenocarcinoma.