MOR agonists inhibit CXCL12-mediated Akt and ERK phosphorylation in cortical neurons. The effect of DAMGO (1 or 10 μM) or endomorphin-1 (100 nM) on Akt and ERK1/2 phosphorylation induced by CXCL12 (20 nM, 15 min) was studied by Western blot. A general opioid receptors antagonist, naloxone (NALX, 50 μM) (A, B), or a MOR-selective antagonist, CTAP (1 μM, D) was used to determine receptors involved. After blotting with phosphospecific antibodies, membranes were stripped and reblotted using antibodies against total Akt or total ERK1/2. Graphs report average ± SEM of P-Akt or P-ERK band density from three independent experiments. ** P < .001 versus control; ˆˆP < .001 versus CXCL12 alone.