Moreover, in the intracranial-orthotopic xenograft GBM mouse model [37], mice treated i.v. with free- or PLGA nanoparticle-encapsulated Retro-Tf-D-LP4 showed significantly lower tumor volume (by up to 90% for free peptide) (Figure 7D, 7E and Supplementary Figure 5). Here, TF is linked to glioblastoma.