KIT and neoplasm: These IL-6+/-/Pax5+/- B-ALLs are histologically, phenotypically and genetically similar to IL-6+/+/Pax5+/- B-ALLs, and FACS analyses revealed a CD19+/-B220+IgM-cKit+/-CD25+/- cell surface phenotype for tumor cells that extended through bone marrow (BM), peripheral blood (PB), spleen and lymph nodes (Supplementary Fig. 5) and infiltrated non-lymphoid tissues like liver and intestine (Supplementary Fig. 6).