Multiple signalling pathways are involved in themechanism by which insulin stimulates hepatic glycogen synthesis. In this study we used selective inhibitors of glycogen synthase kinase-3 (GSK-3) and an allosteric inhibitor of phosphory-lase (CP-91149) that causes dephosphorylation of phos-phorylasea, to determine the relative contributions of inactivation of GSK-3 and dephosphorylation of phos-phorylaseaas alternative pathways in the stimulation of glycogen synthesis by insulin in hepatocytes.