Adapter protein, which negatively regulates T-cell receptor (TCR) signaling. Inhibits T-cell antigen-receptor induced activation of nuclear factor of activated T-cells. Involved in the negative regulation of positive selection and mitosis of T-cells. May act by linking signaling proteins such as ZAP70 with CBL, leading to a CBL dependent degradation of signaling proteins (By similarity). Homodimer. Interacts with phosphorylated CBL, SYK and LAT. Homodimerization and interaction with phosphorylated CBL occurs via its C-terminal domain. Interacts with PDGFRB and EPHA2. Interacts with phosphorylated proteins ZAP70; CD3Z; VAV1 and LCP2 via its SH2 domain (By similarity). Colocalizes with endosomes. The C-terminal domain is essential for the homodimerization and the interaction with CBL. While the interaction with CBL is apparently mediated via the hydrophobic region of this domain, the highly charged region is apparently required for the homodimerization (By similarity). Phosphorylated.