Since no SOX2-targeting E3 ubiquitin ligase has yet been identified in glioblastoma cells, we tested the role of four E3 ubiquitin ligases (CDH1-APC, CUL4A, UBR5, and WWP2) which have been demonstrated to target SOX2 in other cellular contexts through an RNA interference-based approach in GSCs29–32. Here, UBR5 is linked to glioblastoma.