FMR1 and fragile X syndrome: The RhoA pathway appears to be intact in the Fmr1 KO Fragile X syndrome model mouse (Lauterborn et al., 2007) but we have obtained evidence that TBS fails to engage other GTPases and downstream elements involved in the stabilization of cytoskeletal changes in these mice (Chen et al., 2010; Seese et al., 2012).