Loss of STAT1 affects the stem and progenitor compartment in steady-state hematopoiesis. (A) Dot plot showing normalized STAT1 expression in cell types across the Dahlin landscape. The size of each dot indicates the proportion of cells with normalized expression level >0, and the color intensity shows the levels of STAT1 expression. (B) Violin plots showing normalized STAT1 expression in immature cell types in Nestorowa’s scRNA-seq dataset. Mean ± standard deviation indicated in overlaid box. (C) The frequency of T cells was reduced in STAT1-deficient bone marrow. (D) The frequency of pre-granulocyte-macrophage progenitors (PreGM) was increased in STAT1-deficient bone marrow. Flow cytometry was performed, and PreGM progenitors were defined as Lin⁻Sca1⁻cKit⁺CD41⁻CD16/32⁻CD105⁻CD150⁻. (E) The frequencies of MPP3 and MPP4 were reduced in STAT1-deficient bone marrow. Flow cytometry was performed, and multipotent progenitor MPPs were defined as the following: MPP1 (Flk2⁻CD150⁺CD48⁻LSK), MPP2 (Flk2⁻CD150⁺CD48⁺LSK), MPP3 (Flk2⁻CD150⁻CD48⁺LSK), and MPP4 (Flk2⁺CD150⁻CD48⁺LSK). (F) The frequency of ESLAM HSCs was increased in STAT1-deficient mice. Bone marrow ESLAM HSCs were defined as CD45⁺CD150⁺CD48⁻EPCR⁺ cells. Data are shown as mean ± standard error; asterisks indicate significant differences by Student t test (∗P < .05; ∗∗P < .01).