GFAP and neoplasm: •Tumor formation in mice with concurrent heterozygous BRAFV600E expression and homozygous deletion of Ink4a-Arf upon Ad-Cre injection, but not in mice with BRAFV600E expression alone•Tumors exhibit strong immunoreactivity for Olig2, GFAP and Nestin•Tumors have impaired capacity to differentiate into neurons, OLs and astrocytes;•Tumors have high proliferative rate•Diffuse invasion throughout the cerebral hemisphere and white matter tracts