CD226 and neoplasm: Interestingly, compared to the NK cells in the peripheral blood of healthy donors, those derived from ascites in patients with advanced ovarian cancer (OC) exhibited a decreased expression of the activating receptor CD226 [105], which implies that the anti-tumor functionality of CD226 might rely on both extra- and intra-tumoral heterogeneity, akin to what is seen with CD112 [97].