Characterization of surface receptor expression on KLRG1⁻ and KLRG1⁺ mouse NK-cell subsets. Spleen cells were isolated from CX3CR1^+/GFP mice and stained with anti-NK1.1, anti-CD3, and anti-KLRG1 together with the indicated surface marker. Histograms show expression levels of the indicated molecules on KLRG1⁻, KLRG1⁺/CX3CR1-GFP⁻ and KLRG1⁺CX3CR1⁺ cells within NK1.1⁺CD3⁻ NK-cell gate. Control for m157-Fc (Ly49H) staining was NKG2D-Fc followed by PE-conjugated anti–human IgG, while anti-Ly49C/I and anti-Ly49G2 staining controls were PE-conjugated anti–mouse IgG2a/b and anti–rat IgG, respectively (data not shown). Numbers in the histogram plots indicate the percentage of positive cells of a representative analysis of 3 experiments performed.