LRP1 and central nervous system cancer: In one of these studies, angiopep-2, a ligand of lipoprotein receptor-related protein 1 (LRP1) present in glial cells, was conjugated with the surface of a pegylated PAMAM dendrimer (PAMAM-PEG-Angiopep) in order to target glioma cells and deliver tumor-necrosis-factor-related apoptosis-inducing ligand (TRAIL) to the C6 glioma cell line and brain-tumor-bearing ICR and nude mice.