Although the recent use of the S1P analog fingolimod/FTY720, which activates S1P receptors, to treat MS has fueled research on the direct effects of S1P on oligodendrocytes [38], to our knowledge, our data provide the first demonstration of a central role for EVs-associated S1P in OPC migration, the first key step in myelin repair. Here, MBTPS1 is linked to myeloid sarcoma.