The protein encoded by this gene is essential for T-cell proliferation and survival, cytokine production, and T-helper type-2 development. Several alternatively spliced transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, Jul 2011],function:Involved in T-cell activation, the induction of cell proliferation and cytokine production and promotion of T-cell survival.,online information:CD28 entry,similarity:Contains 1 Ig-like V-type (immunoglobulin-like) domain.,subunit:Homodimer, disulfide-linked. Interacts with DUSP14. Binds to CD80/B7-1 and CD86/B7-2/B70.,tissue specificity:Expressed in T-cells and plasma cells, but not in less mature B-cells.,