Inhibition of PI3K, Src, or Akt has no affect on 5-HTP-induced head twitches in βarr2-KO mice. Inhibitors of PI3K (LY294002), Src (PP2), or Akt (AKTi) have no effect on 5-HTP-induced head twitches in βarr2-KO mice. Time course of head-twitch responses (A) and the total number of head twitches (B) observed in βarr2-KO mice that were pretreated for 10 min with either vehicle (Veh; 1% DMSO in dH2O, i.c.v.) or LY294002 (LY; 125 ng, i.c.v.), PP2 (300 ng, i.c.v.), or AKTi (55 ng, i.c.v.) before 5-HTP administration (200 mg/kg, i.p.). Mean ± SEM are shown.