Delayed onset of B lymphoma in NKR-P1B-deficient mice expressing the Eµ-myc transgene. (A) Kaplan-Meier representation of palpable tumor appearance in Eµ-myc.Nkrp1b^+/+, Eµ-myc.Nkrp1b^+/−, and Eµ-myc.Nkrp1b^−/− mice. Statistical analysis was performed by log-rank test, and the P value is indicated. (B) Flow cytometric analysis of B220, IgM, and Clr-b expression on B lymphoma cells from affected organs (lymph nodes, spleen, and thymus) from Eµ-myc.Nkrp1b^+/+ and Eµ-myc.Nkrp1b^−/− mice after disease onset and from healthy WT mice. The percentage of gated cells from each organ is indicated. Clr-b expression on gated B lymphoma cells is represented on the histograms by a dark line; isotype control by a gray line. Clr-b median fluorescence intensity (MFI) values are normalized to isotype control IgM MFI (Clr-b/isotype Ig MFI), and are shown on respective plots. (C) Graphical representation of Clr-b expression levels on mature (IgM⁺), immature (IgM^–), and all B lymphoma cells taken together, in the spleen and lymph nodes of Eµ-myc.Nkrp1b^+/+ and Eµ-myc.Nkrp1b^−/− mice relative to the expression of Clr-b on mature B cells in WT mice. Vertical columns represent Clr-b/isotype Ig MFI ratio, and error bars represent SD. The horizontal dotted line represents the Clr-b/isotype Ig MFI ratio on mature B cells (B220⁺IgM⁺) from WT mice (arbitrarily set to 1.0). Statistical analysis was performed by Student t test, and P values are indicated. Ig, immunoglobulin.