Glucagon-like peptide 2 (GLP-2) is an endogenous hormone with potent and specific intestinotrophic activity in vivo and in vitro. The aim of this study was to define the initial signal transduction mechanisms mediating the proliferative actions of GLP-2 on intestinal epithelial cells.The proliferative actions of GLP-2 on the human Caco-2 cell line were assessed. Specific G-protein inhibitors, pertussis and cholera toxin, were used to characterize the roles of early signal transduction mechanisms in mediating the proliferative actions of GLP-2 in these cells.GLP-2 directly stimulated proliferation in the Caco-2 cells. GLP-2 stimulated proliferation was (1) inhibited in a dose-dependent fashion by both pertussis and cholera toxin and (2) augmented by 2',5'-dideoxyadenosine. Proliferation rates were inversely proportional to changes in intracellular cAMP concentration.Our findings suggest that a G-protein-linked signaling pathway is involved with GLP-2 bioactivity in the intestinal epithelial cell line Caco-2.