DNAM-1 (CD226) is a ~65 kD glycoprotein expressed on cell surface of T cells, NK cells, monocytes/macrophages, platelets and megakaryocytes and a subset of B cells and a member of the immunoglobulin (Ig)-superfamily containing 2 Ig-like domains of the V-set. The ligands for CD226 are the poliovirus receptor (CD155) and its family member nectin-2 (CD112), which are broadly expressed on epithelial, endothelial and neuronal cells. CD226 is physically associated with LFA-1 in NK cells and activated T cells, and involved in LFA-1-mediated signaling.