CEACAM5 and neoplasm: In immunohistochemistry, a panel of different antibodies, such as carcinoembryonic antigen (CEA), gastrin-releasing peptide (GRP), cytokeratin (CK) 5/6, thyroid transcription factor 1 (TTF-1), p63, and thrombomodulin (CD141), is applied for biomarker detection on tumor cells.5, 6