TGFB1 and glioblastoma: TGF-β appears to be pro-tumorigenic in GBM and other cancers through tumor-intrinsic stimulation of cancer survival, epithelial-to-mesenchymal transition (EMT) or analogous processes, treatment resistance, invasiveness, and tumor-extrinsic immunosuppression mechanisms in the tumor microenvironment (TME) that foster cancer immune evasion [20–27].