{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"CD71, also known as Transferrin Receptor Protein 1 (TfR1) is a protein encoded by the TFRC gene. CD71 is required for iron delivery from transferrin to cells. It is most highly expressed on placental syncytiotrophoblasts, myocytes, basal keratinocytes, hepatocytes, endocrine pancreas, spermatocytes, and erythroid precursors. The level of transferrin receptor expression is highest in the early erythroid precursors through the intermediate normoblast phase, after which expression decreases through the reticulocyte phase. The high level of CD71 within erythroid precursors makes it an excellent marker for erythroid components within bone marrow biopsy specimens without interference from mature erythrocytes."}]}]}