TFRC and neoplasm: Previously, our group identified the nuclear localization of TfR1 in tumor tissues by employing magnetoferrin, which consists of iron oxide nanoparticles and heavy-chain ferritin (a ligand of TfR1), for histological staining.35 To validate this phenomenon more comprehensively, we developed a panel of monoclonal antibodies against the intracellular domain of human TfR1 via hybridoma technology, the specificity of which was confirmed through Co-IP assay and flow cytometry.