Detection of tumor-specific markers revealed similar numbers of cancer cells that were positive for lung adenocarcinoma-specific (TTF1 and CK7) or squamous-cell-carcinoma-specific (p40 and PanCK), carcinogenesis-related (AhR, AhRR, and CYP1A1 for tobacco smoking), and proliferation activity (Ki-67) markers expressed on the ex vivo cell preparations and, in parallel, on the histological sections obtained from the same tumor samples and simultaneously stained in the immunofluorescence and immunochemical assays (Figure 1, Figure 3A–C, Figures S1 and S2). The gene discussed is TTF1; the disease is cancer.