ADCY1 and fragile X syndrome: Consistent with the finding that enhancement of ADCY1 expression causes elevated ERK1⁄2 activity [11] and a panel of FXS-associated behavior (e.g., hyperlocomotion and social deficits) [12], genetic reduction of Adcy1 attenuates the elevated ERK1⁄2 signaling and the aforementioned behavioral abnormalities in Fmr1 KO mice [10].