A study on glycogen synthase kinase (GSK)-3 was presented. The isolation, characterization and regulation of GSK-3 activity was discussed. The role of GSK-3 in the Wnt signaling pathway was studied. The inhibition of GSK-3 by GBP/FRAT, GSK-3 phosphorylation of β-catenin and APC and regulation of GSK-3 by other signaling pathways was also described.