Apo-Human transferrin (suitable for cell culture) is the iron-free form of transferrin that acts as a ligand for transferrin receptors (Transferrin receptor) to facilitate the release of iron from endothelial cells. This compound represents an iron-deficient environment and can directly bind with hephaestin to convert Fe2+ (ferrous ions) to Fe3+ (ferric ions). Apo-Bovine Transferrin is likely to work in conjunction with iron transporter 1 to mediate iron efflux.