Fig. 1.

GSK3b and growth regulation. GSK3b activity is suppressed by the insulin/IGF1 and WNT signaling pathways. In the resting state, GSK3b is constitutively active and suppresses growth signaling, translation, and glycogenesis by phosphorylating multiple targets. Activation of Akt by the insulin signaling pathway leads to phosphorylation and suppression of GSK3b activity. GSK3b is also active in the absence of WNT signaling leading to inhibition of mTORC1 and cell growth. Conversely, active mTORC1 inhibits GSK3b activity in a negative feedback loop through S6K