Phosphorylation of PDGFRβ following DRD4 versus PDGF-BB stimulation. (A) Differential pattern of phosphorylation of the PDGFRβ elicited by PDGF-BB and DRD4 in CHO-K1 cells overexpressing DRD4 and FLAG-PDGFRβ (CHO/DRD4-PR). (B) Time course of dopamine-stimulated phosphorylation of endogenous PDGFRβ and ERK1/2 in CHO/DRD4 in the presence or absence of AG1295 (10 μM). AG1295 was pre-incubated with the cells for 1 h before agonist stimulation. (A-B) CHO/DRD4 or CHO/DRD4-PR was stimulated for 5 min, or for the time indicated, with 10 ng/mL PDGF-BB or 1 μM dopamine. IP: immunoprecipitation; IB: immunoblot.