TFRC and central nervous system cancer: Fluorescence density of PAMAM-PEG-Tf/TMZ in TfR+ glioma stem cells (GSCs) was significantly higher than that of matched non-stem cells and active apoptosis of tumor cells could be observed after the uptake of PAMAM-PEG-Tf/TMZ, suggesting that targeting transferrin receptors to deliver TMZ is a potential GSC-mediated treatment method (182).