PTPRZ1 and myeloid sarcoma: In terms of the impact of astrocytic EVs on OPC maturation, we found that EVs from young astrocytes had protein tyrosine phosphatase zeta (PTPRZ), which has been shown to be critical not only for the maturation of OLs from OPCs66 but also in functional recovery from demyelinating lesions in multiple sclerosis (MS)67.