Osteoblast-specific transcription factor Osterix is a zinc-finger transcription factor that required for osteoblast differentiation and new bone formation. The function of Osterix can be modulated by post-translational modification. Glycogen synthase kinase 3 alpha (GSK3 alpha) is a multifunctional serine/threonine protein kinase that plays a role in the Wnt signaling pathways and is implicated in the control of several regulatory proteins and transcription factors. In the present study, we investigated how GSK3 alpha regulates Osterix during osteoblast differentiation. Wide type GSK3 alpha up-regulated the protein level, protein stability and transcriptional activity of Osterix. These results suggest that GSK3 alpha regulates osteogenic activity of Osterix. (C) 2013 Elsevier Inc. All rights reserved.