Fig. 4

Correlation between the GPCR desensitization and transactivation of EGFR. Cells expressing D2-like receptors (1.7–2.1 pmol/mg protein) were pretreated with vehicle or 200 nM AG1478 for 30 min, followed by treatment with 1 or 10 μM DA for 5 min. The cell lysates were immunoblotted with antibodies against phospho-ERK1/2 and ERK2. A HEK-293 cells expressing D₃R or D₄R were treated with 1 μM DA. **p < 0.01 compared with other groups in D₃R-expressing cells; ^###p < 0.001 compared to their respective vehicle-treated groups in D₄R-expressing cells (n = 3). B HEK-293 cells expressing D₂R or K149C-D₂R were treated with 10 μM DA. **p < 0.01 compared with the corresponding vehicle-treated groups in WT-D₂R-expressing cells (n = 3); ^#p < 0.05 compared with other groups of the cells expressing K149C-D₂R (n = 3). C HEK-293 cells expressing D₃R or C147K-D₃R were treated with 1 μM DA. **p < 0.01 compared with other groups in WT-D₃R-expressing cells; ^##p < 0.01, ^###p < 0.001 compared with the corresponding vehicle-treated groups of the cells expressing C147K-D₃R (n = 3)