GUCY2C and neoplasm: We investigated the GCC protein expression in tumor specimens obtained from a total of 627 individuals with various GI malignancies consisting of both CRC and non-CRC tumors, including esophageal (n = 130), gastric (n = 276; both 180 primary and 96 metastatic), pancreatic (n = 136), and colorectal (n = 85, with matching primary lesions and liver metastasis) tumors.