MED1 and neoplasm: This lack of toxicity in these organs could be due to one or a combination of the rapid tissue clearance of the RNA nanoparticle, our tumor-specific HER2 aptamer ligand design and the inability of RNA nanoparticles to enter the cells in these organs, as well as the tissue-specific roles of MED1 and its lack of key biological functions in these organs, etc. Together, these findings support that our biosafe pRNA-HER2apt-siMED1 nanoparticle represents a highly promising new therapeutic regimen for potential future breast cancer treatment to overcome resistance.