CD96 antigen, also designated T cell surface protein tactile (T cell activation, increased late expression) precursor, is a type I membrane protein and is a member of the immunoglobulin supergene family of proteins. The gene encoding for the CD96 protein maps to chromosome 3q13.13-q13.2. During the late phases of the immune response, CD96 is involved in adhesive interactions of activated, both helper and cytotoxic, NK and T cells. It interacts with CD155. CD96, shows increased expression after NK and T cell activation. It can also be found actively engaging diseased cells and moving in inflamed areas after NK and T cells have moved through the endothelium. CD96 is involved in antigen presentation and/or lymphocyte activation. The protein, which may form a homodimer, is expressed on normal T cell lines and some transformed T cells.