(A) FLT3 expression on MACS-selected CD34⁺ BM cells. Three gates with different light scatter characteristics (R1-R3) were chosen to analyze FLT3 expression on differently sized cells. Cells were stained and analyzed as described in Fig 2. (B) After dual scatter gate setting on purified CD34⁺ cells (bottom left) the two indicated sort windows were used to select CD34⁺FLT3⁺ and CD34⁺FLT3⁻ cells for CFC and CAFC assays (bottom right).