β-catenin induces T-cell lymphomas. (A) CD4/CD8 profile of β-catenin–dependent lymphomas. Thymocytes from the indicated mice or thymic lymphomas were stained with antibodies against CD4, CD8 and analyzed by FACS. (B) Surface expression of TCRβ and intracellular expression of β-catenin in the indicated subsets analyzed by FACS. Thymocytes were surface stained with antibodies against CD4, CD8 as well as TCRβ. To evaluate intracellular β-catenin expression, surface-stained thymocytes were permeabilized and stained with anti–β-catenin FITC. Profiles presented in panels B-C are representative of 4 independent experiments. (C) Western blot analysis of β-catenin protein expression in total thymocytes isolated from LckCre (lanes 1-2), LckCre-Ctnnb^Δex3 (lane 3), and CD4Cre-Ctnnb^Δex3 (lane 4) mice, as well as LckCre-Ctnnb^Δex3 (lane 5) and CD4Cre-Ctnnb^Δex3 lymphomas (lanes 6-7). GAPDH was used as loading control. (D) Fraction of DP thymocytes and transformed cells in S/G2/M phase of the cell cycle. Thymocytes or lymphomas were stained with antibodies to CD4, CD8 followed by intracellular staining with 7AAD. DP cells were gated and the percentage of cells in the S/G₂/M phase from 4 to 6 independent experiments was averaged and plotted in the bar histograms. Error bars represent standard error values.