Time course of pERK activation in 3HA‐hCB1 HEK cells (A, C, E) and pplss‐3HA‐hCB1 HEK cells (B, D, F) on stimulation with CP (A, B), WIN (C, D) or THC (E, F), following >16 h pretreatment in the absence or presence of PTX. Combined data (n = 5) were normalized to the level of pERK induced by treatment with PMA for 5 min (100%) and U0126 for 30 min (0%).