RT changes during normal B-lineage differentiation. (A) CD34⁺ CB cells were transplanted into immunodeficient mice and subsequently regenerated. B-lymphoid differentiation intermediates were isolated by FACS using the cell surface markers shown with associated approximated temporal expression patterns. (B) RT profiling method. (C) Exemplary RT profiles highlighting (pink) differences between immature (red) and mature (blue) B cells. (D) Unsupervised clustering analysis of RT-variable regions identified specific RT signatures (labeled in gray boxes). Dendrogram at the top shows the correlation of all samples based on the 10 350 RT-variable 50-kb segments identified. The heat map shows the RT ratios [= log₂(early/late)]. (E) Early human hematopoiesis transcriptome data²²  was used to measure gene expression patterns within each RT signature. RT signatures from panel D contained 274 genes with transcriptional patterns coordinated with their RT program. (F) Heatmap of expression patterns for known hematopoietic regulators within the RT signatures from panel D. Exemplary genes for each RT signature are shown. CM, common myeloid progenitors; EP, early progenitors (CD34⁺CD38^–); GM, granulocyte-monocyte progenitors; LP, late progenitors (CD34^–CD19⁺); M, myeloid-erythroid progenitors; ME, megakaryocytic-erythroid progenitors; MP, middle progenitors (CD34⁺CD19⁺); Prog, progenitor; T, normal T cells.