GSK3 alpha (Glycogen synthase kinase 3 alpha) is a 483-amino acid protein (~53kDa), belongs to the Ser/Thr family of protein kinases, Cdc2/cdkx subfamily, GSK3 subsubfamily, which also includes GSK3 beta. GSK3 is a multifunctional serine/threonine kinase that is usually inactivated by serine phosphorylation in response to extracellular cues. GSK3 is a key regulator of numerous signalling pathways, including cellular responses to Wnt, receptor tyrosine kinases and G-protein-coupled receptors and is involved in a wide range of cellular processes, ranging from glycogen metabolism to cell cycle regulation and proliferation. GSK3 alpha is implicated in the control of several regulatory proteins including glycogen synthase and transcription factors.