Epithelial morphogenesis and intestinal cancer: new insights in signaling mechanisms.

In this review, the major signal transduction pathways that have been shown to play an important role in intestinal homeostasis are highlighted. Each of them, the Wnt, Notch, Hedgehog, and Bone Morphogenetic Protein, as well as growth-factor regulated Receptor Tyrosine Kinases are depicted with a special emphasis through their involvement in stem cell maintenance and their role in intestinal tumorigenesis. Finally, we discuss recent data on the final steps of tumor progression, notably the formation of distant metastases. This multistep process is highly complex and still far from being understood while being of major importance for the survival of patients with digestive cancer.