miRNA expression profile of CLL and CD19⁺ normal cells. (A) The relative abundance of each miRNA species is plotted as a percentage of total miRNAs cloned. ■ indicates average of the values observed in the 9 CLL samples processed; □, pool of RNA from CD19⁺ cells from 8 different healthy donors. miRNAs representing at least 0.5% of total miRNAs on average in CLL are reported. (B) The relative abundance of the 4 miRNAs displaying differential expression between CLL samples (■) and POOL (□) is plotted as percentage of total miRNAs cloned.