INTRODUCTION e human colon is lined with a single layer of epithelial cells that undergoes continuous self-renewal by long-lived tissue stem cells compartmentalized into basic proliferative units (crypts), each of which is a nger-like invagination into the lamina propria connective tissue of the colon. Signicant progress has been made recently in the molecular identication and characterization of intestinal stem cells [1,2], which are located at the base of the crypts, where they give rise to transit-amplifying cells that are committed to dierent cell lineages (goblet cells, enterocytes, and enteroendocine cells). e transit-amplifying cells and their dierentiated progenies migrate up the crypts toward the intestinal lumen into which they are shed aer apoptosis and detachment from the underlying stroma.