TTF1 and lung cancer: Accumulating literatures have documented that miR-7, as a promising tumor suppressor, could regulate the biological behavior of human lung cancer cells.1, 12, 13 Moreover, our previous research works also showed that overexpression of miR-7 could inhibit the growth of human lung cancer cells.17, 18 Therefore, we further investigated whether expression of miR-7 operated by TTF-1 promoter could affect the growth of human lung cancer cells in vitro.