Conversely, for the Pt-3–derived cells, in addition to positivity for CD19, CD10, CD38, CD45, and HLA-DR, there was also plasma-membrane expression of CD20, which indicated that their B-ALL was of a more differentiated type than for the Pt-1 and Pt-2 cells (Fig. 5a). This evidence concerns the gene PTPRC and acute lymphoblastic leukemia.