GFAP and oligodendroglial tumor: GFAP-EGFRvIII; GFAP-Cre/RictorloxP/loxP glial tumors were strongly APC and GalC positive by immunohistochemical staining (Figure 4D&E) and to a lesser extent GFAP positive consistent with a mixed astrocytic-oligodendroglial tumor.