One potential tumor-specific target is carcinoembryonic antigen (CEA), as 74.5–90% of gastric cancers have been shown to express CEA by immunohistochemistry.26,27 We have previously utilized the poorly differentiated gastric adenocarcinoma cell line, MKN45, to create orthotopic mouse models of gastric cancer. This evidence concerns the gene CEACAM5 and gastric cancer.