Echinomycin treatment did not reduce normal hematopoietic progenitor cells and HSCs. Wild-type CD45.1⁺ mice received (1) sublethal irradiation alone (top lane); (2) sublethal irradiation and 2 cycles of echinomycin therapy starting same day as started in group 3 (middle lane), or (3) sublethal irradiation, intravenous injection of tertiary relapsed CD45.2⁺ AML blasts (1 × 10⁶/mouse), and 2 cycles of echinomycin therapy starting day 8 after infusion of AML (bottom). Mice were then observed for 150 or 165 days and killed, and harvested BM cells were stained as defined in the Materials and methods to assess frequency of CD45.1⁺ (A) LSK, MP, CMP, GMP, and MEP and (B) LSK, MP, LT-HSCs, MPC, MPP, and ST-HSCs. The data were reproduced in 2 independent experiments. An additional example of A is shown in supplemental Figure 3; an additional example of B is shown in supplemental Figures 5 and 6.