WIF1 and glioblastoma: This adds a novel mechanism of WNT pathway deregulation observed in GBM that include genetic and epigenetic inactivation of negative regulators, such as Dickkopf, the family of Secreted Frizzled-Related Proteins (SFRPs), and the WNT inhibitory factor 1 (WIF1) that affect the canonical, and in the case of WIF1 also the non-canonical WNT pathway [4, 33, 38, 39].