Following cardiac perfusion with cold phosphate buffered saline (Fisher Scientific), brain and tumor tissues were dissected and fixed in 4% paraformaldehyde overnight, embedded in paraffin, and sectioned at 5 μm thickness. Tumor tissue sections were deparaffinized, rehydrated and stained using standard immunohistochemistry and immunofluorescence protocols, as described before [26 (link), 32 (link), 39 (link)]. The following antibodies were used: phospho-Erk (Thr202/Tyr204), Ki67/Mib-1, Met, phospho-Met (Tyr1234/1235), Pten, phospho-S6 ribosomal protein (Ser235/236) (Cell Signaling Technology), Gfap (Biocare Medical), Olig2, Sox2 (Abcam), Tuj1 (Sigma), 53BP1 (Santa Cruz Biotechnology), horseradish peroxidase-conjugated secondary antibodies (Vector Laboratories), and Alexa488/568-conjugated secondary antibodies (Thermo Fisher). For immunofluorescence, 4’,6-diamidino-2-phenylindole counterstain (DAPI, Vector Labs) was used to visualize nuclei. Ki67 indices were quantified by manually counting at least 500 nuclei in the area of highest staining, as described [40 (link)]. All immunohistochemistry images were acquired on a Keyence BZ-X800 microscope using the Keyence BZ-X software (Keyence). All immunofluorescence images were acquired on a Zeiss Axio Imager 2 microscope using the Zen Imaging software (Carl Zeiss).