ERVW-1 and myeloid sarcoma: Therefore we performed in vitro experiments on cells transcribing MSRV and syncytin-1, and with HERV-Wenv protein on the plasmamembrane, i.e. peripheral blood mononuclear cells (PBMC) from MS patients and MSRV-positive healthy donors (HD) and astrocytes, that were exposed to EBV or to its major envelope glycoprotein 350 (EBV gp350).