Figure 1

Western blots characterizing ERK phosphorylation by DSLET. (1A) HEK-δ-OR cells were serum-starved overnight prior to exposure to DSLET (1 pM – 1 μM for 5 minutes). After DSLET exposure, cell lysates were prepared and ERK phosphorylation was determined by SDS PAGE, followed by immunoblotting of proteins onto nitrocellulose. Immunopositive bands correspond to α-tubulin, and the phosphorylated forms of ERK 1 and ERK 2. (1B) Inhibitory effects of naltrindole (10 μM) or PTX (100 ng/ml) on DSLET-stimulated ERK phosphorylation. Naltrindole was added 60 minutes prior to DSLET, while PTX was added 18 hours before the δ-OR agonist. After DSLET exposure, cell lysates were prepared and ERK phosphorylation was determined by SDS PAGE, followed by immunoblotting of proteins onto nitrocellulose. Immunopositive bands correspond to the phosphorylated forms of ERK 1 and ERK 2. The immunoblots are representative of an experiment that was repeated three times.