GUCY2C and colorectal carcinoma: GUCY2C is ordinarily expressed strictly on the apical side of the intestinal tight junctions, whereas in colorectal cancer (CRC) and other gastrointestinal tumors it is expressed ectopically in other sites such as gastric, esophageal, and pancreatic tissues, making GUCY2C an appealing antigen for a biotherapeutic approach17,25,37–39.