TFRC and neoplasm: Transferrin (Tf) is an endogenous protein that transports iron into cells through the cell membrane's TfR.[49] There is a growing body of evidence that TfR expression in HCC is much higher than that in healthy tissues because liver cancer cells show upregulated iron metabolism.[50] Therefore, Tf has been utilized as a specific tumor‐guiding unit to improve the accumulation of targeted fluorescent prodrugs in tumor tissues.