MMP14 and glioblastoma: In the context of TGFβ-blocking therapy in GBM, the advantage of our approach is that (1) it overcomes the problem of penetration through the blood–brain barrier, allowing for an efficient delivery of TGFβ blockade with a potential to also reach tissue-invading GBM cells; (2) as transgene expression under MMP14 promoter is restricted to intratumoral myeloid cells,17 systemic side effects such as keratoacanthomas8 are expected to be minimized.