Human GFI1 is equivalent to murine Gfi1 in hematopoiesis. (A) Schematic representation of the murine Gfi1 locus and the targeted alleles. (B) Western blot of nuclear extracts of Gfi1^36N/36N, Gfi1^+/+, Gfi1^−/−, and Gfi1^36N/36N+neo thymocytes. (C) Western blot of nuclear and cytosolic extracts of Gfi1^36N/36N and Gfi1^36S/36S thymocytes. (D) Total number of B220⁺ cells in the bone marrow (per both hind limbs; n = 23 Gfi1^+/+, n = 13 Gfi1^−/−, n = 13 Gfi1^36N/36N, and n = 9 Gfi1^36S/36S). *P ≤ .05. (E) Total number of thymocytes (n = 9 Gfi1^+/+, n = 5 Gfi1^−/−, n = 5 Gfi1^36N/36N, and n = 6 Gfi1^36S/36S). *P ≤ .05. (F) Total number of HSCs (Lin⁻, Kit⁺, Sca-1⁺, CD150⁺, CD48⁻ bone marrow cells) in both hind limbs (n = 15 Gfi1^+/+, n = 7 Gfi1^−/−, n = 3 Gfi1^36N/36N, and n = 4 Gfi1^36S/36S). *P ≤ .05. (G) Flow cytometric analysis showing the staining of bone marrow cells for Gr1 and Mac1 surface markers. (H) Total number of monocytes in the bone marrow (per both hindlimb; n = 19 Gfi1^+/+, n = 6 Gfi1^−/−, n = 6 Gfi1^36N/36N, and n = 4 Gfi1^36S/36S). *P ≤ .05. (I) Total number of granulocytes in the bone marrow of the indicated mouse strains per hindlimb (n = 19 Gfi1^+/+, n = 6 Gfi1^−/−, n = 6 Gfi1^36N/36N, and n = 4 Gfi1^36S/36S). *P ≤ .05. (J) Wright-Giemsa staining of bone marrow cytospins (original magnification ×100, Leitz DMRB from Leica, Micropublisher digital color camera, QImaging, Northern Eclipse Version 7.0 software).