NTRK2 and central nervous system cancer: In addition to strong immunostaining of TrkB.T1 across genetically diverse RCAS-driven gliomas (Supplementary Fig. 5b), additional analysis of genetically diverse mouse tumorsphere lines reveals increased expression of TrkB.T1 compared with TrkB.FL (Supplementary Data 3, Supplementary Fig. 7a, b) suggesting that while overexpression TrkB.T1 can enhance PDGF-driven gliomas in vivo, this variant also predominates over TrkB.FL in all rodent gliomas analyzed and may be selected for in an oncogenic context.