HPK1-C sensitizes toward activated T-cell death in vivo. (A) Thymocytes and naive T cells from non-tg and HPK1-C tg mice were analyzed for expression of HPK1 and HPK1-C by Western blotting (WB). (B) CD4 and CD8 (top panels) or CD3 and B220 (bottom panels) surface expression of thymocytes (top panels) or spleenocytes (bottom panels) from non-tg or HPK1-C tg mice was analyzed by flow cytometry. The percentage of cells in the respective quadrants is indicated. (C) Activated T cells of HPK1-C tg mice or non-tg littermates were analyzed by flow cytometry for CD95 surface expression. The filled histogram shows the isotype control. (D) HPK1-C tg mice or non-tg littermates were analyzed for AICD in vivo by intravenous injection of 10 μg of anti-CD3 antibodies or isotype control antibodies (control). After 24 hours, splenocytes were stained with anti-TCRβ, anti-B220, anti-CD4, or anti-CD8 antibodies and analyzed by flow cytometry. Depicted bars correspond to individual mice of 3 independent experiments (nos. 1, 2, and 3) with standard deviations given for triplicate measurements.