Anti-µ–induced calcium flux in CLL cells that express high vs low levels of miR-155. (A) The height of each column in the histogram describes the increase in fluorescence intensity after anti-µ stimulation of CLL cells that expressed high miR-155 vs low miR-155, as indicated at the bottom of the histogram. (B) Anti-µ–induced calcium mobilization in CLL cells after transfection with mimic-ct (top graph) or miR-155 (lower graph). The relative mean fluorescence intensity in intracellular calcium is plotted as a function of time. The arrow labeled “IgM” indicates the time at which the anti-µ was added to the cells. In the histogram at the bottom, the height of each column corresponds to the mean increase of fluorescence intensity after anti-µ stimulation for samples transfected with either mimic-ct or miR-155 microRNA, as indicated at the bottom by a “+”. (C) Anti-µ–induced calcium mobilization in CLL cells after transfection with oligo-ct or miR-155 inhibitor. The relative mean fluorescence intensity in intracellular calcium is plotted as in panel B. The height of each column in the bottom histogram corresponds to the increase of fluorescence intensity after anti-µ stimulation for samples respectively transfected with either control-ct or miR-155 inhibitor, as indicated at the bottom by a “+”. (D) The height of each column in the histogram describes the increase in fluorescence intensity after anti-µ stimulation of ZAP-70–negative CLL cells with high miR-155 or low miR-155, as indicated at the bottom of the histogram. Statistical significance was determined by the unpaired Student t test (P < .05). IgM, immunoglobulin M.