AKT1 and neoplasm: Completely upstream of that signaling pathway, we measured the complete activation of Akt through phosphorylation on serine 473 [2]; we also measured GSK3β (glycogen synthase kinase 3 beta) phosphorylation on serine 9, a direct target of activated Akt, and an effective measure of GSK3β inhibition that reduces its ability to act as a tumor suppressor [43].