IELps from RasGRP1-deficient animals show signs of impaired TCR signaling. (A) Representative expression of CD122 on IELp cells (CD4^−/dullCD8^−/dullNK1.1⁻TCRβ⁺CD5⁺) from WT and 1KO mice. Data were obtained from the indicated number of mice over 17 individual experiments; WT (n = 17), 1KO (n = 11). (B) Representative PD-1 and Helios expression on DP thymocytes and CD122⁻ IELp from WT mice and CD122⁺ IELp cells from WT and 1KO mice. (C) Frequencies of PD-1⁺Helios⁺ cells within CD122⁻ and CD122⁺ IELp cells from the indicated mice. Data were obtained from the indicated number of mice over nine individual experiments; WT (n = 9), 1KO (n = 5). *, P < 0.05; ***, P < 0.001 (unpaired Student’s t test). Error bars indicate SEM.