NRP1 and neoplasm: Theranostically, polysiloxane nanoparticles combining a magnetic resonance imaging (MRI) contrast agent, a photosensitizer and the NRP1-targeting motif KDKPPR can be employed to destroy tumor neovessels in glioblastoma, because they accumulate in the tumor vessel wall and show no cytotoxicity unless after exposure to light during photodynamic therapy [393].