GFAP and neoplasm: Loss- and gain-of-function combined with scRNA-seq reveal that tumor cells with higher levels of ASCL1 relative to OLIG2, as seen in the Olig2-CKO and Ascl1-OE tumors, favor activation of a NSC/astrocyte program, characterized by high expression of GFAP and a highly migratory or diffuse phenotype (Fig. 10c, d).