CXCR7 regulates CXCL12-promoted chemotaxis of T lymphocytes. (A) T lymphocytes were nucleoporated with 5 μg SCR or CXCR7 siRNAs and tested for their ability to migrate in response to CXCL12 at the indicated concentrations. Data represent 3 independent experiments performed in duplicate. (B) T lymphocytes were tested for their ability to migrate in response to CXCL12 at the indicated concentrations in the presence of either mouse isotype control (IgG1) or the anti-CXCR7 mAb (9C4) at 10 μg/mL. The amount of input CD4⁺-gated T cells that migrated to the lower chamber was compared with that of SCR siRNA- (A) or IgG1-treated cells (B) that migrated toward 0.3 nM CXCL12 (arbitrarily set at 1, and accounting for, on average, 3% of input cells). Data represent 3 independent experiments. *P < .05, compared with lymphocytes nucleoporated with SCR siRNA or incubated with IgG1.