Coexpression of FLT3 and CD34 in BM, CB and PB gated on cells with low side scatter (lymphocytes and progenitor cells), intermediate side scatter (monocytes), or high side scatter (granulocytes). Cells were labeled with anti-CD34-FITC and biotinylated FLT3-specific MoAb SF1.340 and stained with streptavidin-phycoerythrin (SA-PE). A mixture of IgG1-FITC and IgG1-biotin stained with SA-PE was used as control. Fifty thousand cells were analyzed on a FACSCalibur flow cytometer.