TFRC and breast carcinoma: Protein expression of TfR in normal and malignant breast tissue was assessed by immunohistochemistry using a tissue microarray (TMA) of 107 human samples (99 breast cancer and 8 adjacent normal breast), stained for TfR with the FDA-approved anti-CD71 antibody MRQ-48, and scored taking as reference the darkest stain (highest expression) present within each tissue sample (S1D Fig).