It has been reported that GA-amide is a TrkA agonist, which can induce TrkA phosphorylation.18,19 Consistent with this report, we found that TrkA was phosphorylated at Y751 and Y490 in GSCs (Supplementary Fig. 5a, b); thus, we sought to determine whether the activity of TrkA is related to the inhibition of glioma. This evidence concerns the gene NTRK1 and central nervous system cancer.