METTL3 and central nervous system cancer: When loaded into EVs secreted by human bone marrow stromal cells (hBMSCs), miR-1208 crosses the BBB, acting as a tumor suppressor by inhibiting key pathways involved in glioma progression, by negatively regulating the expression of Methyltransferase-like 3 (METTL3) and suppressing the TGF-β pathway.