CpG-ODN–stimulated CLL cells from PB exhibit a pattern of expression similar to leukemic cells from LNs. Purified PB leukemic B cells were stimulated with CpG-ODN alone or in combination with IL-2, and p27 expression levels were evaluated by Western blot. A representative blot is shown (A top). The average result from analysis of stimulation on 16 patients is shown as p27/Actin ratio calculated by densitometric analysis (A bottom). miRNA expression in the cells from the same experiments was evaluated by TaqMan miRNA assay, and the results were expressed as fold change (2^−ΔΔCt; B). Statistical significance was evaluated by the Wilcoxon test. Purified CLL PB cells stimulated with CpG-ODN alone or in combination with IL-2 were stained with anti-p27 antibody (green), propidium iodide (PI; red) to identify nuclei, and Ki67 (blue) antibody (C; 63×/1.25 NA oil objective). Confocal analysis of stained cells shows, compared with unstimulated cells (first and fourth columns, 63× and 240× magnification, respectively), a marked reduction of p27 expression and a parallel increase in Ki67 expression in cells stimulated with CpG-ODN (second and fifth columns, 63× and 240×, respectively) and in combination with IL-2 (third and sixth columns, 63× and 240×, respectively). CTR indicates control.