Ligands for CD226 include CD155 (poliovirus receptor, PVR) and CD112 (nectin-2 or poliovirus receptor-related 2, PVRL2), which are expressed on epithelial cells, endothelial cells, APCs, and tumor cells; thus, the interaction between CD226 and its ligands is more often discussed in the context of tumor immunity (83, 84). Here, CD226 is linked to neoplasm.