CHIR99021 is an aminopyrimidine derivative that inhibits GSK3? and GSK3? with IC50 values of 10 and 6.7 nM, respectively.{19045} When tested against twenty different protein kinases, this inhibitor shows greater than 500-fold selectivity for GSK3. CHIR99021 activates glycogen synthesis in CHO-IR cells (EC50 = 0.763 ?M) and in isolated type 1 diabetic rat skeletal muscle. A single oral dose (30 mg/kg) of CHIR99021 enhances in vivo glucose metabolism in a rodent model of type 2 diabetes. CHIR99021 has also been shown to induce the reprogramming of murine and human somatic cells into stem cells.{19047,16878}