Flow cytometry analysis showed that Prmt1 KO significantly decreased the leukemia burden (cell number of GFP+ leukemia cells and GFP+Gr1+ myeloid cells) (Figure 2G,H; Figure S2C, Supporting Information), and the cell number of LSPCs including GFP+LSK cells, GFP+ long‐term HSCs (GFP+LT‐HSCs), GFP+ short‐term HSCs (GFP+ST‐HSCs) (Figure 2I,J; Figure S2D, Supporting Information), as well as GFP+ granulocyte‐macrophage progenitor (GFP+GMP) and GFP+ common myeloid progenitor (GFP+CMP) cells in CML mice (Figure 2K,L; Figure S2E, Supporting Information). The gene discussed is PRMT1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.