The results of immunohistochemical assessments showed that Thyroid transcription factor 1 (TTF-1 or NKX2–1) and Cytokeratin 7 (CK7), which are sensitive and specific expressions (positive rate more than 70%) in NSCLC and especially in adenocarcinoma, were all significant positive (Figure 3). Here, KRT7 is linked to adenocarcinoma.