– Lymphocyte cytosolic protein 2(LCP2)contains a SAM domain and a SH2 domain. It is highly expressed in spleen, thymus and peripheral blood leukocytes, T-cell and monocytic cell lines, but expressed at lower level in B-cell lines. LCP2 was originally identified as a substrate of the ZAP-70 protein tyrosine kinase following T cell receptor (TCR) ligation in the leukemic T cell line Jurkat. It is phosphorylated after T-cell receptor activation by ZAP70, ITK and TXK, which leads to the up-regulation of Th1 preferred cytokine IL-2 during post-translational modification. Studies using LCP2-deficient T cell lines or mice have provided strong evidence that SLP-76 plays a positive role in promoting T cell development and activation as well as mast cell and platelet function.