Figure 3. Guggulsterone stimulates phosphorylation of ERK1/2. Dose-response and time-course for guggulsterone-induced phosphorylation of ERK1/2 in H508 (A), SNU-C4 (B) and HT-29 cells (C).

For dose-response experiments, cells were treated with the indicated concentrations of guggulsterone for 5 min at 37°C. For time-course experiments, cells were treated with guggulsterone (20 µM) for the indicated times at 37°C. Phosphorylation of ERK1/2 was determined by immunoblotting with anti-phospho-ERK1/2 antibody. Immunoblotting for ERK2 was used as a loading control. Numbers between immunoblots represent densitometry. Experimental/control (exp/cont) ratios were calculated after normalizing each test band to the respective control band. Immunoblots are representative of at least 3 separate experiments.