TFRC and cancer: Siderophores and iron have become relevant in carcinogenesis because cancer cells demand increased iron concentrations to sustain rapid proliferation, which increases the activity of many iron-binding molecules [transferrin, the transferrin receptor, ferritin and lipocalin 2 (Lcn2)] while decreasing the activity of the cell iron exporter ferroportin (Figure 1B) (11, 16–18).