GSK3B and osteosarcoma: Interestingly, a previous study showed that cGKII activated C/EBPβ through phosphorylation of glycogen synthase kinase-3β (GSK-3β) in osteosarcoma cells [42], and our recent study showed that cGKII induced chondrocyte hypertrophic differentiation through the GSK-3β phosphorylation [36].