Expression of SHIP1 protein in CLL cells that expressed high vs low levels of miR-155. (A) Expression of SHIP1 in CLL cells that expressed high (n = 21) or low (n = 24) levels of miR-155, as indicated at the bottom of the histogram. The height of each column corresponds to the mean MFIR of cells stained for SHIP1 in each subgroup. Error bars indicate the standard deviation of the mean. Statistical significance was determined by unpaired Student t test (P < .05). (B) Expression of SHIP1 in representative CLL samples, CLL#1 (Rai stage 1 at diagnosis, mutated IGHV, ZAP-70–negative, Δ peak anti-µ–induced MFIR = 7) or CLL#2 (Rai stage 2 at diagnosis, mutated IGHV, ZAP-70–positive, Δ peak anti-µ–induced MFIR = 32), after transfection with mimic-ct (control microRNA) or miR-155 microRNA, as indicated at the bottom of each panel. (C) Expression of SHIP1 in representative CLL samples, CLL#3 (Rai stage 2 at diagnosis, unmutated IGHV, ZAP-70–positive, Δ peak anti-µ–induced MFIR = 4.2) or CLL#4 (Rai stage 0 at diagnosis, mutated IGHV, ZAP-70–negative, Δ peak anti-µ–induced MFIR = 1.4), after transfection with oligo-ct (control microRNA) or miR-155 inhibitor, as indicated at the bottom of each panel. In (B) and (C) data are presented from immunoblot analyses (top panels) or flow cytometry (bottom panels), respectively. After the immunoblots were probed with anti-SHIP1, they were stripped and probed with anti–β-actin to monitor the uniformity of protein loading. The numbers between the immunoblot panels provide density ratios of the SHIP1 band relative to that of the β-actin band, normalized with respect to the ratio observed in control-treated samples. The histograms in the bottom panel depict the mean MFIR of CLL cells stained for SHIP1 after transfection with (B) mimic-ct or miR-155 mimic or (C) oligo-ct or miR-155 inhibitor, as indicated at the bottom of each histogram. Statistical significance was determined by paired Student t test (P < .05).