GSK3B and fragile X syndrome: We treated Fmr1 KO mice and their wild-type littermates using three different treatment regimens that affect signaling via different pathways that have been implicated in FXS: mTORC1-S6K1 (the S6K1 inhibitor PF-4708671;“PF”), GSK-3β (lithium; “Li”), and ERK (metformin; “Met”) and analyzed the response of two markers associated with cell membrane and biosynthesis: Ras and HK1, respectively.