Inhibitor of glycogen synthase kinase-3 (GSK-3); derived from FRAT1, the mammalian version of GSK-3-binding protein. Binds to GSK-3, inhibiting its interaction with axin, and also blocks GSK-3-catalyzed phosphorylation of axin and β-catenin. Does not affect GSK-3-mediated phosphorylation of glycogen synthase or eIF2B.
