This mouse (K832, Figure 4a far right panel, Table 1) displayed a single uniform population of B220loCD19+IgM–CD25+CD244hi cells in the bone marrow which largely effaced all other populations and matched EB tumor cell surface marker phenotype, suggesting that tumor cells developed from the unusual B220loCD244+ late pre-B population present in EB and Ebf1+/– bone marrow. This evidence concerns the gene EBF1 and neoplasm.