Copy number amplifications of the CDK4, EGFR, and PDGFRA loci and mutations in the NF1 locus define GBM states: neural progenitor-like (NPC-like), oligodendrocyte-progenitor-like (OPC-like), astrocyte-like (AC-like), and mesenchymal-like (MES-like) states. The gene discussed is EGFR; the disease is glioblastoma.