Unbiased clustering analysis of genome-wide expression profiles indicate that CD19⁺CD127⁺ and CD19⁺CD127⁻ cells are most similar to pro-B and large pre-B cells and small pre-B cells, respectively. Clustering analysis was performed without bias for known genes or subsets. All probe sets were ranked based on the maximum difference in expression that was observed between any 2 arrays (excluding the CD34⁺Lin⁻ and pre-pro-B cells). (A) Hierarchical clustering (complete linkage) using 1 − r as a distance measure based on the 3826 (threshold at log₂ value 2) probe sets that showed the most variation between any 2 samples. (B) Correlation of the CD127⁺ and CD127⁻ cells with each of the freshly isolated cord blood CD34⁺Lin⁻ cells and pediatric BM B-lineage cell subsets.