Furthermore, iMLLr-B-ALL patients commonly show CNS disease either at presentation or at relapse,43 NG2 has a role in the developing brain and is associated with melanoma cell migration/metastasis.21, 22 Our functional data following a limiting dilution approach in NSG mice serially transplanted with highly purified NG2+ or NG2− MA4+ blasts confirms the high-risk evolution of MA4+ iB-ALL since as many as 83% and 100% of patient samples are able to transfer the leukemia onto primografts and secondary recipients, respectively, despite transplanting a limited number of cells. This evidence concerns the gene CSPG4 and melanoma.