In order to determine the differences between normal astrocytes and TAAs and to identify genes and pathways increased in TAAs we generated PDGF-driven gliomas in GFAP-GFP transgenic mice, which express GFP under the control of the human GFAP promoter [30], and used FACS to specifically collect samples enriched for TAAs from microdissected low-grade gliomas and GBM. Here, GFAP is linked to glioblastoma.