TFRC and colorectal carcinoma: Immunofluorescence confocal microscopy clearly demonstrated the nuclear localization of TfR1 in various tumor cell lines, including HCT-116 (human colorectal carcinoma), A549 (human lung carcinoma), Hep G2 (human hepatic carcinoma), and U-87 MG (human glioma) (Supplementary Fig. 3).