Epithelial markers and the markers of non-small cell lung cancer (NSCLC), such as pan-cytokeratin, CAM5.2, claudin-4, CK5, p40, and CK7, in all tested cases were not expressed, and single cases showed focal weak TTF-1 and p63 expression. The gene discussed is CLDN4; the disease is non-small cell lung carcinoma.