The interaction of glycogen synthase kinase-3 (GSK-3) with the cell cycle.

GSK-3 is a multifunctional protein kinase known to play a pivotal role in the regulation of metabolism, the cytoskeleton and gene expression. It also interacts with the cell cycle in a number of ways. GSK-3 forms part of both Wnt and Hh signalling pathways and hence controls expression of a number of cell cycle regulatory genes. Prominent among these is cyclin D1. GSK-3 also phosphorylates cyclin D1 to promote its nuclear export and subsequent degradation. In this chapter we examine how GSK-3 mediates these effects and consider how therapeutic strategies may be developed to specifically target these pathways.