CD155 (PVR), expressed as a membrane-bound protein on the surfaces of dendritic cells, macrophages, and tumor cells, not only interacts with CD96 but also binds other Ig superfamily receptors, such as TIGIT (T cell immunoreceptor with Ig and ITIM domains) and CD226 (platelet and T cell activation antigen 1; DNAM-1), which share sequence homology in the first V domain of the extracellular region. Here, CD226 is linked to neoplasm.