TTF1 and lung cancer: Recent evidence showed that TTF-1, as a lineage-specific oncogene, was dominantly expressed in lung cancer, but not other types of cancers, and its expression level was closely correlated with the prognosis of lung cancer patients.18, 19, 20 MicroRNA-7 (miR-7) is a unique member of miRNAs and plays an important role in the progression of various tumors.21, 22 Our previous works showed that miR-7 overexpression could obviously reduce the growth and metastasis of human lung cancer cells in vitro and in vivo.23