Additional RNA ISH for cxcr4a, another gene up-regulated in hMYC pre-B vs. T-ALL (Fig. S5A), showed identical staining to cd79b and opposite staining to lat in two different specimens (Fig. S5B-C), demonstrating hMYC+/cd79b+/cxcr4a+/lat- cells correspond to B-lineage GFPlo cancers. This evidence concerns the gene CD79B and acute lymphoblastic leukemia.