Furthermore, recent data indicate that several genes encoding upstream inhibitors of wnt signalling, such as SFRP1, SFRP2, and NKD2, are often epigenetically silenced by promoter hypermethylation in glioblastomas of WHO grade IV and that these alterations occur independently of common β-catenin mutations [25]. This evidence concerns the gene SFRP1 and glioblastoma.