Based on several markers and immunochemistry staining, NOS carcinoma can be divided into two subcategories: (1) NSCLC favoring ADC, occurring in 40% of cases and usually expressing both TTF-1 and napsin-A; and (2) NSCLC favoring squamous tumors, occurring in 10% of cases and characterized by p40-positive stains. The gene discussed is TTF1; the disease is non-small cell lung carcinoma.