The four major cell types of GBM are shown in Figure 3C: tumor cells (PTPRZ1, OLIG2, PDGFRA, DLL3, AQP4, and CLU), immune cells (PTPRC, P2RY12, CD163, CXCL1, FCGR3B, and FCN1), proliferation cells (MKI67), and normal cells (MOG). The gene discussed is PDGFRA; the disease is glioblastoma.