CD226 and neoplasm: A cogent example of the functional connection between chemotherapy and therapeutical immunomodulation is the finding that several genotoxic agents or drugs, such as inhibitors of proteasome, histone deacetylases, or the HSP-90 molecular chaperone, can increase the expression of NKG2D or DNAM-1 ligands, thus facilitating the activation of NKG2D/DNAM-1-expressing lymphocytes (e.g., NK cells, NKT cells, and CTLs) against tumor cells, including MM [17, 19–23].