HMOX1 and glioblastoma: reported that pharmacological inhibition of HO-1 in BM-DMs isolated from glioblastoma samples, with the HO-1 inhibitors ZnPPIX and OB-24, significantly reduced cell-to-cell- (i.e. PD-L1/PD-1) and soluble-dependent (i.e. IL-10) immunosuppressive mechanisms.