GBM is a heterogeneous tumor composed of multiple cell types, including both tumor and stromal cells.

<p>(A) Immunohistochemical staining of mouse PDGF-driven glioma identified multiple tumor regions composed of different cell types. (B) PDGF-HA oncogene expressed from tumor cells colocalized with Olig2 staining by IHC. (C) FACS analysis of tumors generated in Olig2-eGFPL10a mice with PDGF-RFP bicistronic retrovirus identified tumor cells as Olig2+. Scale bar, 100 µm.