Next, we transplanted MLL-AF9-GFP-transduced BL/6 lineage−Sca-1+c-kit+ cells (LSKs) into non-irradiated BL/6 mice and Il21−/− mice (BL/6 AML and Il21−/− AML, respectively) (Figure 1D). This evidence concerns the gene IL21 and acute myeloid leukemia.