SOX21 and cancer: Interestingly, amongst oligodendrocytes, astrocytes and ependymal candidate driver genes we find numerous genes that were previously associated with glial tumors (for instance Adgrg1, Cdc42ep4, Mdk, Pou3f2, Sox21, Idh1 or Cfl2, supplementary tables), which suggests that their misexpression in cancer reverts the cells to an earlier developmental and proliferative stage.