The aptamer TTA1 specific to the extracellular matrix protein tenascin-C and labeled with fluorescent rhodamine RedX or radionuclid 99mTc, has demonstrated, after i.v. administration in GBM-xenografted models, rapid perivascular delivery (10 min), quick tumoral uptake (maximum 1 h), good diffusion into tumoral parenchyma (within 3 h), long persistence in tumor (18 h), a high tumor-to-blood ratio (50) within 3 h, and rapid clearance from systemic circulation [10,132]. The gene discussed is TNC; the disease is glioblastoma.