FMR1 and fragile X syndrome: These findings provide the first identification of links between GSK3 and social behaviors and suggest that dysregulated GSK3 may contribute to some of the social impairments associated with loss of FMRP and that these might be partially remedied by lithium administration, also supporting the utility of Fmr1 knockout as a means to identify mechanisms underlying social impairments common among ASD and FXS patients and for exploration of therapeutic interventions that may enhance social interactions.