Furthermore, HO expression is related to the immunosuppressive function of dendritic cells and dysfunction of T cells [110,111]; thus, HO inhibition by shRNA or ZnPP improves dendritic cells maturation and revokes the unresponsiveness of CD4 and CD8 T-effector cells in neuroblastoma, glioma cells, and multiple myeloma [107,108,110]. The gene discussed is HMOX1; the disease is plasma cell myeloma.