(A–B) Activation. Splenocytes were stimulated as indicated, and CD69 (A) and CD98hc (B) measured by flow cytometry; n=3 per group; performed twice. (C–D) In vitro proliferation. Splenocytes were stimulated as indicated and analyzed by flow cytometry; performed twice. (E–F) In vivo clonal expansion. T cells from CD4-Cre+, RIAMfl/fl, OT-1 (eFluor670-labeled) and control RIAMfl/fl, OT-1 littermates (CFSE-labeled) were mixed equally, transferred into RIPmOVA mice, and assessed by flow cytometry from pancreatic lymph nodes 3 days later; n=3 mice per group; performed twice.