Transferrin and the transferrin receptor: of magic bullets and other concerns.

Transferrin (Trf) is a highly conserved serum glycoprotein mostly known for its iron transport capacity. As iron is an indispensable nutrient for cell division, Trf and its receptor have long been used as targets of pharmacological intervention mostly for cancer therapy and for diagnosis in inflammation. In recent years several independent pieces of work including data from our group, indicated that Trf can also have an iron independent role in the immune system. In this article new emerging roles of Trf and its receptor on iron independent processes and in drug delivery are reviewed.