Pep-1 (Cys-Gly-Glu-Met-Gly-Trp-Val-Arg-Cys) functions as a BBTB-penetrating and glioma targeting peptide by specifically binding to interleukin-13 receptor-α2 (IL-13Ra2) with high affinity, followed by internalization into glioma cells (Pandya et al., 2012). Here, IL13RA2 is linked to glioma.