SB216763 is a cell-permeable ATP-competitive inhibitor of glycogen synthase kinase 3α (GSK3α, IC50 = 34 nM) and GSK3β isozymes (Coghlan et al.) GSK3 is a serine/threonine protein kinase that is inhibited by a variety of extracellular stimuli including insulin, growth factors, cell specification factors, and cell adhesion