PD-L1, also called human programmed cell death ligand 1, is a transmembrane protein that plays a major role in suppressing the immune system during particular events such as pregnancy, tissue allografts, autoimmune disease, virus infection, and cancer. PD-L1 binds to its receptor PD-1 on activated T cells, B cells, and myeloid cells, to modulate activation or inhibition. Upregulation of PD-L1 can allow the cancer cell to evade the host immune system.
PVR, abbreviated as poliovirus receptor, is a transmembrane glycoprotein belonging to immunoglobulin superfamily. CD155 is involved in the cellular poliovirus infection in primates, and intercellular adherent junctions between epithelial cells.