CXCL12 confers stronger calcium flux in ZAP-70⁺ CLL cells. (A) Representative calcium flux profiles of 3 ZAP-70⁺ (filled symbols) and 3 ZAP-70⁻ (open symbols) CLL cells in response to 8nM CXCL12 stimulation. Measurements represent an average of triplicate data points that have been normalized to buffer controls. (B) The maximal fluorescence signal from the calcium flux was averaged between the ZAP-70⁺ (n = 3) and ZAP-70⁻ (n = 3) CLL cells and was found to be significantly different on the basis of unpaired Student t test (P < .01). Data shown are median ± SD.