Adapter protein that plays a role in T-cell receptor (TCR)-mediated activation of signaling pathways. Required for T-cell activation and integrin-mediated T-cell adhesion in response to TCR stimulation (PubMed:27335501). Interacts with SKAP1, LCK and FYN. The phosphorylated form interacts with LCP2. Recruited to membrane rafts and immunological synapse after TCR stimulation. Expressed in T-cells (at protein level). Widely expressed. Phosphorylation is required for its function in T-cell activation.