Figure 3

Western blot characterizing the effect of PP1 on ERK phosphorylation by EGF (5 ng/ml for 5 minutes) or DSLET (1 μM for 5 minutes). HEK-δ-OR cells were serum-starved overnight prior to exposure to EGF or DSLET. In some instances, cells were exposed to PP1 (10 μM) for 60 minutes prior to DSLET or EGF. After agonist 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, ERK 1, and ERK 2. The immunoblot is representative of an experiment that was repeated three times.