CD44 and glioblastoma: By attaching toxic payloads to nanoparticles, tumour-specific targets expressed in GBM cells and responsible for tumorigenesis can be targeted; examples of these include antigens (i.e., A2B5), differentiation clusters (i.e., CD15, CD33, CD44, or CD133), receptors of cytokines (i.e., interleukin13 receptor), and several proteins (i.e., EGFR, Integrin-a6, α5β3, ανβ3 or L1CAM).