CD27 is part of the Tumor Necrosis Factor (TNF) family of receptors and is lymphocyte specific. Murine CD27 is expressed on the great majority of both αβ and γδ T lymphocytes, on a small population of peripheral B cells and on a very small subset of B220+ cells in the bone marrow. Murine CD27 is found on all thymocytes except a subset of CD4-CD8-precursors. There are two known basic functions of CD27 signaling. First, the binding of CD27 to CD70, a protein which is also expressed in T and B cells, provides costimulatory signals in lymphocyte proliferation and immunoglobulin production. Second, the association of CD27 with intracellular Siva, a proapoptotic protein, results in the induction of apoptotic events.Synonyms: CD27L receptor, T-cell activation antigen CD27, T14, TNFRSF7, Tumor necrosis factor receptor superfamily member 7