STAT5 is required for early NK-cell development in the bone marrow. (A) Flow cytometry of Stat5f/fNcr1-iCreTg mice and littermate controls. Representative dot plots indicate the percentage of gated Lin−CD122+ NKPs (DX5−NK1.1−) and gated Lin−CD122+ mNKs (DX5+NK1.1+) cells. (B) Bar graphs show the percentage of Lin−CD122+ cells, NKPs (DX5− NK1.1−, gated on Lin−CD122+), and mNKs (DX5+ NK1.1+, gated on Lin−CD122+) in the bone marrow (n = 8 STAT5f/f; n = 7 STAT5f/fNcr1-iCreTg, **P = .0014, Mann Whitney U test). (C) Bar graphs show absolute cell number of Lin−CD122+ cells, NKPs, and mNKs in the bone marrow (n = 8 STAT5f/f; n = 7 STAT5f/fNcr1-iCreTg, **P = .0014, Mann Whitney U test). (D) Histograms show the expression of indicated differentiation markers as percentages. (A-D) Data are representative of at least 3 independent experiments. (D) n ≥ 4 per genotype.