Figure S3. ERK inhibition can downregulate EGFR expression. (A) AsPC-1 cells were treated with indicated concentrations of PD98059 for 24, 48, and 72â h. p-ERK and EGFR protein levels were determined. (B) AsPC-1 cells were transfected with scramble or ERK siRNA for 48â h to evaluate the protein expression of ERK and EGFR. Actin was loaded as an internal control. (TIF 440 kb)