GUCA2B (uroguanylin) is an endogenous activator of the guanylate cyclase-2C receptor found to be down regulated 8-fold in adenoma, and its expression is detected in blood and urine [71].Therefore, GUCA2B could be regarded as a non-invasive biomarker for the early detection of CRC. This evidence concerns the gene GUCA2B and colorectal carcinoma.