After transfection of TfR-siRNA into T47D or MDA-MB-231 cells, these cells became less sensitive to the cytotoxic effect of TfR-lytic hybrid peptide (5 μM for T47D cells and 10 μM for MDA-MB-231 cells) compared with that of cells transfected with the scramble-siRNA as a control (Figure 3B), and it was also confirmed that siRNA used in this study was not toxic to normal and cancer cell lines (T47D, MDA-MB-231, HC, and PE) as shown in additional file 2. This evidence concerns the gene TFRC and cancer.