Markers expressed at significantly different levels in ALL cells and in CD19⁺CD10⁺ B-cell progenitors as determined by flow cytometry. Shown are mean fluorescence intensity (MFI) values obtained in CD19⁺ leukemic lymphoblasts from BM samples of patients with newly diagnosed ALL (“L”) and BM CD19⁺CD10⁺ cells from healthy donors or from patients with leukemia in remission and no evidence of MRD (“N”). Each symbol indicates results of one sample; horizontal bars correspond to median values within each group.