Guanylin family, described in recent 10 years, is a series of small peptides （including guanylin, uroguanylin and lymphoguanylin） with structural and functional similarities to heat-stable enterotoxins （STs） elaborated by various pathogenic bacteria. They are abundance of cysteines and are endogenous activators of guanylyl cyclase-C （GC-C） receptors. Immunoreactive guanylin family peptides are localized in many human organs and tissues, especially in gastrointestinal tract and kidney, and play an important role in regulation of water and salt homeostasis. Recent studies showed that the mRNA levels of guanylin family peptides were down-regulated in colorectal cancers; oral intake of uroguanylin might suppress polyp formation in Apc（Min/+） mouse, and 111In-labeled-ST peptide analog might specifically target human colon cancers. These evidences highlight that guanylin family may have a potential application in diagnosis and therapy effects of colorectal cancers.
