IgM-induced calcium mobilization in ZAP-70⁻ CLL B cells transduced with Ad-ZAP-70 or Ad-ZAP-70-KA³⁶⁹. (A) The fluorescence of labeled CLL cells induced by treatment with anti-μ is indicated on the y-axis over time (in seconds, as indicated on the x-axis). The horizontal dotted line in each panel provides the basal fluorescence of labeled cells prior to treatment. The arrow indicates the time when the cells were treated with anti-μ (IgM). The top panel shows the changes in calcium flux ([Ca²⁺]_i) detected in ZAP-70⁻ CLL cells transduced with Ad-lacZ (Control); the middle panel shows the [Ca²⁺]_i observed in the same CLL sample transduced with Ad-ZAP-70; and the bottom panel shows the [Ca²⁺]_i observed in the same CLL sample transduced with Ad-ZAP-70-KA³⁶⁹. (B) Peak increases in fluorescence intensity over the basal level in ZAP-70⁻ CLL cells transduced with Ad-lacZ (Control) versus that of CLL cells transduced with Ad-ZAP-70 (top) or Ad-ZAP-70-KA³⁶⁹ (bottom). The lines connect the data points obtained from the same CLL sample, but transduced with Ad-lacZ (control) or Ad-ZAP-70 or Ad-ZAP-70-KA³⁶⁹, as indicated at the bottom of the panels.