There are at least four iron-binding proteins in plasma which carry the potential to either deliver iron to tumor cells or deprive it from them: TF, lactoferrin (LF), FT, and lipocalin (LCN)-2 can bind iron in different forms and their content of and affinity for iron as well as the distribution of corresponding cell surface receptors between normal nucleated cells and tumor cells may determine whether the latter can benefit from these proteins as iron sources (Figure 2). This evidence concerns the gene TF and neoplasm.