GSK3β inhibitor XVIII is an inhibitor of glycogen synthase kinase 3β (GSK3β; IC50 = 64 nM). It induces expression of a luciferase reporter in HEK293 cells expressing wild-type Wnt (EC50 = ~1.25 μM) but not in cells expressing a β-catenin/TCF binding site-mutant Wnt. GSK3β inhibitor XVIII increases β-catenin accumulation in the nucleus of HEK293 cells. It induces proliferation of R7T1 β-cells (EC50 = 1,143 nM), an effect that can be blocked by the COX and Wnt signaling inhibitor sulindac , and rat primary β-cells.
