CCR7 signaling is enhanced in B cells expressing activated ZAP-70. (A) Ramos transfectants prestimulated for 4 hours with 5 μg/mL F(ab′)2 anti-IgM were stimulated with 1 μg/mL CCL21 for 30 minutes (left panel). Only in IgM stimulated Ramos ZAP-70 transfectants, CCL21 stimulation increased the phosphorylation of ERK1/2. CCL21 increased Akt phosphorylation with or without the presence of IgM stimulation. Akt phosphorylation was the highest when ZAP-70 was activated. A slight increase in Akt phosphorylation was observed in ZAP-70–expressing cells before IgM stimulation. In Raji transfectants treated with 1 μg/mL CCL21 for 5 and 30 minutes (right panel), the same enhanced signaling was observed. (B) Ramos transfectants prestimulated with 5 μg/mL F(ab′)2 anti-IgM for 4 hours were stimulated with 250 ng/mL CCL21. MFIR was calculated relative to unstimulated samples. Significant increase in calcium mobilization was observed in BCR-stimulated ZAP-70–positive cells. *P < .05.
