TFRC (Transferrin receptor protein 1, CD71) is a receptor that is required for iron import from transferrin into cells via endocytosis. Transferrin receptor is necessary for development of erythrocytes and the nervous system. A second ligand, the heditary hemochromatosis protein HFE, competes for binding with transferrin for an overlapping C-terminal binding site. TFRC is expressed on blood-brain barrier endothelial cells and is of interest as a means to deliver antibodies and other large molecules into the brain. Furthermore, it is a potential target of inhibition therapy for some cancers including adult T cell leukemia and mantle cell lymphoma. In immunohistochemistry of normal tissue, TFRC has membranous and cytoplasmic positivity in the brain, bone marrow cells and placental trophoblasts, and is also found at variable levels in most other tissues throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804; Progress in Neurobiology. 181: 101665, PMID 31376426; Bulletin de l'Académie Nationale de Médecine. 2019. 203(6): 424-431, DOI: 10.1016/j.banm.2019.04.018;