Intracellular β-catenin protein levels are increased in Eμ-TCL1–induced leukemia cells. Flow staining was performed on lymphocytes isolated from the peripheral blood of tumor bearing Eμ-TCL1 mice (> 10 months old), aged WT mice (> 10 months old), and young Eμ-TCL1 mice (6 weeks old). As shown in the left panels, anti–mouse CD19-APC and CD5-phycoerythrin are used to gate CD19⁺CD5⁺ and CD19⁺CD5⁻ B cells. The right panels show the fluorescence intensity of FITC-conjugated anti–β-catenin in CD19⁺CD5⁺ (dotted line) and CD19⁺CD5⁻ (solid line) B-cell populations. The numbers state the net geometric mean of the fluorescence intensity (Geo Mean_β-catenin − Geo Mean_{isotype control}). Representative data of 3 independent analyses are shown.