IMiDs can epigenetically regulate different genes in MM cells [36, 51, 52], and histone deacetylase (HDAC) or DNA methylation inhibitors can induce NKG2D ligand expression in different cancer cells [53-56]; moreover, a possible role of epigenetic mechanisms in the regulation of PVR/CD155 expression has been also described [57]. The gene discussed is HDAC9; the disease is cancer.