WHIM mutation of CXCR4 enhances chemotactic and calcium flux responses to SDF-1 in PBSCs ex vivo. Transduced and naive nontransduced PBSCs were stimulated with SDF-1 at day 4 of ex vivo culture in a migration (A) or calcium-flux (B) assay. Transduced groups expressed GFP-only (♦), or GFP plus either mutated CXCR4 (▪) or wt CXCR4 (•), while naive nontransduced cells did not express any transgenes (▴). (A) Chemotaxis migration assay. Data are the percentage of loaded cells migrating into the lower chamber in response to 0.5, 1, 5, or 10 nM SDF-1 after 30 minutes of stimulation (n = 8, P < .01 for all comparisons between mutated CXCR4 and any of the 3 other groups, or for comparisons between wt CXCR4 and any of the other groups). (B) Calcium flux assay. Data are the peak of relative fluorescence change (RFC) from the baseline within 30 seconds of stimulation (n = 6, P < .01 for all comparisons between mutated CXCR4 and any of the 3 other groups, or between wt CXCR4 and any of the other groups).