TFRC and central nervous system cancer: Using bEnd.3 cells (over-expressed TfR1) as the model of brain endothelial cells, HUVEC cells (over-expressed HSPG) as the model of neovascular endothelial cells, and U87MG cells (over-expressed HSPG and TfR1) as the model of glioma cells model, cellular association and internalization mechanism was investigated bEnd.3 cells, HUVEC cells and U87MG cells by using Cy5.5 as the fluorescence probe.