Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) are part of a large family of ligands that bind to the epidermal growth factor receptor. While the precise role of these ligands is still unclear, there is little doubt that they play an important role in the development and maintenance of gastrointestinal epithelial continuity. The main ligand for the intestinal EGF receptor (EGFR) may in fact be TGF-alpha, and there is evidence that EGF itself may act as a surveillance factor in adults, only having an effect if the mucosa is damaged.