Interestingly, whereas a PrPC-binding hop/STI1 peptide mimicked the full hop/STI1 protein in the induction of several PrPC-mediated responses in neurons (Zanata et al., 2002; Lopes et al., 2005), the proliferative effect of hop/STI1 upon glioblastoma cells also depended on the hop/STI1:PrPC interaction, but was not induced by the peptide alone (Erlich et al., 2007; Linden et al., 2012). Here, PRNP is linked to glioblastoma.