OLIG2 and medulloblastoma: Co-immunohistochemistry/in situ hybridisation investigations for oligodendrocyte markers identified no co-labelling with the mature oligodendrocyte marker CNPase or the glial progenitor cell marker Olig2+ in both wild type and Ptch1lox/lox;GFAPcre medulloblastoma (S2E–S2H Fig).