PSMB9 and myeloid sarcoma: We showed that the main producers of myelin sheets, i.e. the oligodendrocytes, as well as the macrophages/microglial cells, which express PA28-αβ [39] and golli MBP [40] during EAE, are positive to LMP2 and PA28-αβ staining in MS CNS (Fig. 3).