PVR/CD155 is a transmembrane glycoprotein belonging to the immunoglobulin superfamily. It mediates NK cell adhesion and triggers NK cell effector functions. PVR/CD155 binds two different NK cell receptors: CD96 and CD226, and these interactions accumulate at the cell-cell contact site, leading to the formation of a mature immunological synapse between NK cell and target cell. This may trigger adhesion and secretion of lytic granules and IFN-gamma and activate cytoxicity of activated NK cells. PVR/Cd155 also promotes NK cell-target cell modular exchange, and PVR transfer to the NK cell. This transfer is important in some tumor cells expressing a lot of PVR, and may trigger fratricide NK cell activation, providing tumors with a mechanism of immunoevasion. PVR/CD155 also plays a role in mediating tumor cell invasion and migration. [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/P15151].