TGFB1 and glioblastoma: On the one hand, microglia synthesize and release transforming growth factor-beta 1 (TGF-β1) to support GSC invasion by promoting MMP-9 expression [11]; on the other hand, immunosuppressive microglia promote the formation of an immunosuppressive microenvironment in the GBM by releasing IL-10, regulating the mammalian target of rapamycin (mTOR) pathway or other pathways [12, 13].