PDGFRB and glioblastoma: Using a different approach, our group proved the ability of the anti-platelet-derived growth factor receptor beta (PDGFRβ) Gint4.T aptamer, which we previously generated by GBM cell-SELEX and validated as a high affinity ligand/inhibitor of the receptor in GBM [37, 58] and bone marrow-derived human mesenchymal stem cells [73], to efficiently deliver a drug (Bez 235, PI3K-mTOR inhibitor) to orthotopic (intracranial) GBM xenografts across the BBB.