Fig. 2.

Effect of ketamine on morphine/fentanyl-induced ERK1/2 phosphorylation. SK-N-SH cells were treated for 5 min at 37°C with different concentrations (0–100 μM) of morphine (a) or fentanyl (b) in the absence or presence of ketamine (10 μM) and subjected to western blot analysis using anti-phospho ERK1/2 and anti-tubulin antibodies as described in Materials and methods section. Results are the mean ± SE of six independent experiments in triplicate.