CLEC2C (CD69) is a membrane-bound, type II C-lectin receptor and acts as a costimulatory molecule for T cell activation and proliferation. It is involved in lymphocyte proliferation and functions as a signal transmitting receptor in lymphocytes, natural killer (NK) cells, and platelets. CLEC2C is a disulfide-linked homodimer protein with two differentially glycosylated subunits.