Indeed, several recent studiessupport its role as a cancer biomarker, prognostic factor, and therapeutictarget.−,  Furthermore, TfR1 is widely expressed in variouscancers, including breast cancer, as demonstrated by TfR1 immunohistochemistryof clinical samples from the Human Protein Atlas. To date, biodistribution studies conducted by our group and others have shown tumor-specific accumulationof HFn in tumor-bearing mice, with off-target distribution limitedto the liver and kidneys. Here, TFRC is linked to cancer.