CD226 and plasma cell myeloma: The treatment of multiple myeloma (MM) cells with low doses of chemotherapeutic drugs triggered the expression not only of NKG2D, but also of DNAM-1 ligands in an ATM/ATR-dependent manner promoting cellular adhesion to cells expressing DNAM-1 ligands including CD155 and CD112 (Bottino et al., 2003; Soriani et al., 2009).