GUCY2C and colorectal neoplasm: GUCY2C protein (> 200 specimens) and/or mRNA (> 900 specimens) is present in nearly all primary and metastatic human colorectal tumors, regardless of anatomical location or grade [7, 11–13, 40–44], and is over-expressed by > 80% of colorectal tumors [40, 45, 46].