SCARB1 and cancer: Therefore, the encapsulation of 225Ac in rHDL nanoparticles (225Ac-rHDL) would prevent the release of daughter radionuclide from the transporter biomolecule due to the recoil energy effect and, at the same time, the specific molecular recognition of 225Ac-rHDL by cancer cells that overexpress the SR-BI protein would allow the cytoplasmic internalization of 225Ac in tumor cells to produce ablative radiation doses.