Biochem/physiol Actions Potent and selective inhibitor of GSK-3β and CDK5/p25; potent inhibitor of CDK1/cyclin B (IC50 = 0.035 μM). Application Alsterpaullone inhibits GSK-3β, CDK5/p25, and CDK1/cyclin B. Alsterpaullone has also been studied as an antimanic therapeutic for the acute manic phase of bipolar disorder.