GSK3B and acute myeloid leukemia: Furthermore, the levels of phosphorylated GSK-3β (glycogen synthase kinase 3 beta; p-GSK-3β) at Ser9 in the B-ALL cell lines were significantly lower compared to the levels in the AML cell lines (p = 0.0455) Activation of GSK-3β by dephosphorylation inhibits glycogen synthesis.