ERK1/2 phosphorylation induced by RANTES stimulation of CCR5. Approximately 24 h post-transfection, cell media were changed to DMEM without FBS. 48 h after transfection, the cells were then stimulated with 10 ng/ml RANTES for up to 10 min. After stimulation, cells were harvested in TBS and then lysed with RIPA containing phosphatase inhibitors. Immunoblots were performed using an anti-phospho-ERK antibody or total ERK antibody as a control of loading and of expression. a shows NHERF1 effect on CCR5 dimer. b, quantification of a, where *, p < 0.05 in comparison with CCR5 + pcDNA3. c, NHERF1 effect on the CXCR4-CCR5 heterodimer. d, quantification of c and e, effects of both WT and PDZ1-PDZ2 NHERF1 on ERK phosphorylation in the presence of CCR5 homodimer or the heterodimer. f, quantification of the results in e, top blot. g, quantification of the results from e, bottom blot. Results are representative of three experiments. *, p < 0.05; **, p < 0.01 compared with their unstimulated equivalent, acting as negative controls using two-tailed paired Student's t test.