TFRC and Sepsis: Thus, we evaluated sepsis-induced changes of the two cardinal iron uptake systems, namely, the transferrin- bound iron system (TBI) (composed of the transferrin receptor protein 1 (TfR-1) and cubilin) and the non-transferrin-bound iron system (NTBI) (composed of the divalent metal transporter 1 (DMT-1) and zinc transporters (ZIPs)).