AM1241 is a protean agonist of CB2 based on the different effect observed in various assays (calcium influx, extracellular signal-regulated kinase (ERK) phosphorylatin and cAMP measurement)) and on the switch from neutral antagonism to agonism in the cAMP assay when forskolin concentration is lowered. In [3H]CP 55,940 competition binding assays, AM-1241 displays high affinity at the human CB2 receptor with a Ki value of about 7 nM, whereas its affinity at the human CB1 receptor is more than 80-fold weaker, using membrane preparations from stable HEK and CHO cell lines expressing the recombinant human CB2 and CB1 receptors, respectively.