ENG and neoplasm: The tumor-specific characteristics of the anti-endoglin antibody TRC105 have also been combined with biocompatible, radiolabeled PEGylated mesoporous silica (mSiO2) nanoparticles (64Cu-NOTA-mSiO2-PEG-TRC105), which aggregated specifically at 4T1 breast tumor sites in mice after intravenous administration [68].