Considering potential roles of miRNAs and Smad3 in tumor cell growth and metastasis, we studied functions of Smad3-related miRNAs in lung cancer cell apoptosis, proliferation, and metastasis, and confirmed that miR-206 and miR-140 can suppress tumors as well as regulate phospho-Smad3 (p-Smad3)/Smad3, which can affect TRIB2 and suppress lung adenocarcinoma cell proliferation or metastasis. Here, SMAD3 is linked to lung carcinoma.