In vitro studies demonstrated that the HPPS-mAb was efficiently taken up in a dose-dependent manner by various TfR-expressing tumor cell lines, including CHO cells stably expressing a hybrid of human TfR and green fluorescent protein (CHO-hTfR), human hepatic carcinoma HepG2 cells, human glioblastoma U87 cells, human cervical cancer HeLa cells, and human breast cancer MDA-MB-231 cells. This evidence concerns the gene TFRC and breast cancer.