TROP2, which was originally identified in human trophoblast and choriocarcinoma cell lines [11], is encoded by TACSTD2. TROP2 is not expressed in normal tissue, but is overexpressed in many carcinomas, including colorectal cancer, gastric cancer, SCC of the oral cavity, and pancreatic cancer [5]. This evidence concerns the gene TACSTD2 and gastric cancer.