PDE4DIP and fragile X syndrome: Together, our pharmacological results strenghten the previous molecular work in FMR1 KO mice showing that FXS may involve both production and degradation of cAMP considering that FMRP binds to mRNAs for PDE regulating cAMP (PDE4B, PDE4DIP, PDE8B), but also cAMP and cGMP (PDE2A) (Darnell et al., 2011).