CXCR4 expression is not down-regulated after preincubation with CCL4.

Expression of the CXCR4 chemokine receptor was analyzed on pre-B cells after preincubation for 30 minutes at 37°C with medium alone (shaded part of the histogram) or with CCL4 (100 ng/mL CCL4, black thick line, or 1000 ng/mL CCL4, gray thick line). Black thin line represents the isotype control. Similar results were obtained for the other bone marrow B-cell subsets (pro-B, immature B, mature B cells). The results are representative of 3 experiments using primary human bone marrow B cells.