Trp53 haploinsufficiency and EGFR overexpression cooperated for grade 3 PNST formation in vivo. A: Kaplan-Meier survival plot of the four genetic cohorts analyzed: WT (n = 46), Trp53+/− (n = 43), CNP-EGFR (n = 44), and CNP-EGFR;Trp53+/− (n = 84). B: Necropsy images depict the peripheral nerves targeted for tumor development: dorsal root ganglia, lumbar plexus, subcutaneous nerves, and trigeminal nerves. Arrows indicate tumor location. C: IHC analysis of nerve-associated tumors for H&E staining, toluidine blue (mast cells), Ki-67 (proliferation marker), and S100β (Schwann cell marker) indicates the tumors have features of various grades of Schwann cell tumors. The arrows in indicate Toluidine Blue positive cells. D: IHC for Schwann cell markers Gfap, Nestin, Olig2, and Sox10. Images depicted are from a grade 3 PNST. E: Bar graph depicts breakdown of neurofibroma, grade 3 PNST, or both tumors in each mouse genetic cohort. Tumor type was determined on the basis of histological analysis performed (C and D, Supplemental Figure S2A, and Supplemental Table S1). Statistics were performed with a Fisher's exact test. ∗∗∗∗P < 0.0001. Original magnification, ×400 (C and D). Scale bar = 50 μm (C and D).