protein_function: Involved in T-cell activation, the induction of cellproliferation and cytokine production and promotion of T-cellsurvival. Enhances the production of IL4 and IL10 in T-cells inconjunction with TCR,CD3 ligation and CD40L costimulation(PubMed:8617933). Isoform 3 enhances CD40L-mediated activation ofNF-kappa-B and kinases MAPK8 and PAK2 in T-cells(PubMed:15067037)..
CD28 (Cluster of Differentiation 28) is one of the proteins expressed on T cells that provide co- stimulatory signals required for T cell activation and survival. T cell stimulation through CD28 in addition to the T-cell receptor (TCR) can provide a potent signal for the production of various interleukins (IL-6 in particular). The CD28 gene is mapped to 2q33-q34. CD28 and CTLA-4, together with their ligands, B7-1 and B7-2, constitute one of the dominant costimulatory pathways that regulate T and B cell responses. CD28 and CTLA-4 are structurally homologous molecules that are members of the immunoglobulin (Ig) gene superfamily.