Single-cell sorting of four subpopulations of CD34⁺ BM cells. BM MNCs were stained with an FITC-conjugated anti-CD34 MoAb, APC-conjugated anti-CD38 MoAb, and PE-conjugated anti–c-kit MoAb. As negative controls, FITC-, APC-, and PE-conjugated mouse IgG1 were used. (A) The lymphoblastic region (R1) was gated on the basis of FSC and SSC. (B, C). The gate (R2) was set on CD34⁺ cells. (D) The expression of CD38 and c-kit on CD34⁺ cells were examined. The single cells in the R3, R4, R5, or R6 region were sorted as CD34⁺CD38⁺c-kit⁺, CD34⁺CD38⁻c-kit⁺, CD34⁺CD38⁺c-kit⁻, or CD34⁺CD38⁻c-kit⁻ cells, respectively, using an automatic cell deposition unit equipped with the FACStar^plus flow cytometer, as described in Materials and Methods.