A CD8+T cells from OT‐I Rag2−/−mice expressing wild‐type (LCK) or LCKS59A proteins were stimulated with H‐2Kb‐positive antigen‐presenting cells pulsed with serial dilutions of the OVA (257-264) peptide, the OVA peptide variants Q4 and T4, and VSV, a peptide that is not recognized by the OT‐I TCR. CD69 up‐regulation (left) and TCR down‐regulation (right) were analysed. Data are representative of three independent experiments. 