Identifying miRNAs in normal and malignant B cells. (A) Analytic pipeline for the discovery and validation of known and novel miRNAs in B Cells. Small RNAs from B-cell subsets were subjected to massively parallel sequencing. Raw sequence reads (328 934 149) filtered, mapped to the genome, analyzed by miRDeep, and annotated. Identified miRNA loci were cross-referenced with miRBase13 to distinguish known from candidate novel miRNA. (B) Frequency of reads for miR-20b and their alignment to the genome. The sequence surrounded by a rectangle corresponds to the most abundant and longest mature miRNA sequence that perfectly matched the genome. (C) Outputs of the RNAshapes program that computed the abstract structure of the miRNA precursor, the probability of the predicted structure, and the minimum free energy of folding for the precursor structure for miR-20b. (D) Energetically favorable folding of the miR-20b precursor, with the miRNA mature sequence and the microRNA* sequence highlighted in yellow.