RCAS-TrkB.T1 injected into the brains of postnatal day (P)1 N/tv-a (Nestin-expressing cell of origin) wild-type mice significantly enhanced glioma formation as evidenced by decreased survival in mice injected with RCAS-PDGFB + RCAS-TrkB.T1 compared with mice injected with RCAS-PDGFB only (RCAS-PDGFB + RCAS-TrkB.T1 vs. RCAS-PDGFB alone: median survival 34 days vs. 109 days, Mantel-Cox/log-rank hazard ratio 2.306, 95% confidence interval 0.8999 to 5.909, p < 0.05) (Fig. 5a). This evidence concerns the gene NTRK2 and central nervous system cancer.