MMP9 and glioblastoma: Firstly, Fe3O4-siPD-L1, Fe3O4-siPD-L1@M-BV2 and Fe3O4-siPD-L1@M-BV2 + magnet significantly increased the protein expression of E-cadherin and decreased the protein expression of TGF-β, MMP-9, CD44 and N-cadherin in orthotopic drug-resistant GBM tissue.