CD226 and breast cancer: As with the CD8+ T cells of BM aspirates, NK cells also showed increased expression of at least one target molecule of the TIGIT/PVRIG pathway axis or the CD39/CD73 purinergic pathway in comparison with NMCs (BC: TIGIT, PVRIG, CD226; PC: PVRIG; NSCLC: TIGIT, CD39, CD73; MM: PVRIG, CD226, CD39).