PTPRC and acute myeloid leukemia: Of note, many of these Mac-1+/Gr-1+ cells were also positive for B220; a Mac-1+/Gr-1+/B220+ population has been observed previously in AML caused by overexpression of the CALM-AF10[28], [29]or NUP98-HOXD13[25] fusion genes in mice, and a similar lymphoid-primed multipotential progenitor population has recently been reported in a subset of human AML samples [31].