CD226 and breast neoplasm: Microarray data for NK-cell ligand expression in primary breast tumors showed that the different subtypes express heterogeneous levels of inhibitory HLA members, while some patterns of ligand expression represented the different molecular subtypes, which are characterized by distinct genomic alterations and deriving from different precursor cells, except for NKG2D and DNAM-1 ligands which are expressed in virtually all breast tumors regardless molecular subtype (Mamessier et al., 2011a).