CD226 and acute myeloid leukemia: TIGIT and the poliovirus receptor-related immunoglobulin domain-containing protein (PVRIG, CD112R) are inhibitory receptors that compete with DNAX accessory molecule-1 (DNAM-1, CD226), an activating receptor that is downregulated on NK cells in AML [18], for their ligands poliovirus receptor (PVR, CD155) and poliovirus receptor-related 2 (PVRL2, CD112).