RNA-Seq of primary normal human BM and tonsil fractions identifies FBXW7 transcript variants. (A) FACS analysis of normal human progenitors and B-cell subsets from the BM and tonsils. Flow plots represent 1 of 4 BM donors and 1 of 4 tonsil donors. BM and tonsil donors were distinct. (B) Venn diagram of genes exhibiting differential exon usage throughout human B-cell development. Ensembl gene annotation was used. Cell subsets from 4 BM donors and 4 tonsil donors were analyzed. (C) GO analysis of the 150 genes highlighted in (B). (D) Genomic configuration of the FBXW7 gene (left) and its AFE usage in normal BM subsets (right). Each stacked bar represents means of frequencies of α, γ, and β exon usage across 4 donors.