Figure 3.

ERK1/2 phosphorylation in human D2long dopamine receptors expressed in stably transfected HEK cells. (A) Quinpirole dose response curve for the phosphorylation of ERK1/2. Each point is the mean ± SEM for n > 3 determinations, where each determination was performed in at least quadriplicate. The data for this experiment was fit to a one site fit model where the curve was constrained to zero (vehicle control) and 100%, where it was assumed that the mean value for the response at a dose of 10^–5 Molar quinpirole was the maximum response. For this analysis an EC₅₀ value of 149 nM was obtained. (B) Similar dose responses were performed for SV 293 (●) and SV-III-130s (■). The dose range for the two test ligands included concentrations ≥ 10× the K_i values for binding at D2 dopamine receptors.