TFRC and breast carcinoma: This is of significance given that the TEPP aptamer cross-reacts with the mouse receptors, as shown in the EpCAM-ve/TfR+ve bEnd.3 endothelial cells (Kd 110 nM) (Table 1) or EpCAM+ve/TfR+ve murine 4T1 mammary carcinoma cells (Kd 27 nM) (Supplementary Fig. S2) in vitro, and could compete with binding to human tumor cells in mouse xenograft models.