APOE and glioblastoma: Some examples are the sequence arginine-glycine-aspartate (RGD) used to recognize tumoral cells expressing integrin αvβ3 on their surface [33], the apolipoprotein E modified peptide (pep-apoE), and the peptide of lipocalin-type prostaglandin-d-synthase (L-PGDS) that allow PLGA nanoparticles to cross the blood-brain barrier (BBB) [34] or the phage peptide Pep-1, which show great affinity for the interleukin 13 receptor α2 (a glioblastoma multiforme-associated plasma membrane receptor) [35].