Pax5^+/−Ebf^+/− tumor cells display molecular heterogeneity. (A) Heat map over gene expression patterns in primary sorted CD19⁺CD43^highIgM⁻ ex vivo-analyzed BM pro-B cells from 14-week-old mice and 8 pro-B cells tumors from Pax5^+/−Ebf1^+/− mice. The expression pattern is based on genes differentially expressed >10-fold in any of the tumor samples compared with normal pro-B cells. Red indicates high and blue indicates low expression of mRNA. The data are collected from 2 array experiments from each cell population. (B) Quantitative PCR data generated from primary sorted live lymph node cells from a set of independently generated tumors and primary sorted BM pro-B cells. The data were normalized to the expression of Hprt, and the diagrams present 1 of 2 independent quantitative RT-PCR experiments based on triplicate quantitative RT-PCR reactions.