Fig. 2: NTRK2 splice variant, TrkB.T1 is the predominant TrkB isoform, in human glioma.

a Boxplots for transcript expression of TrkB.FL and TrkB.T1 from brain samples from GTEx project (n = 956) and TCGA (n = 530) LGG and TCGA GBM (n = 166) demonstrate a predominance of TrkB.T1 in glioma samples compared with normal brain. TrkB.T1 transcript displayed in teal, TrkB.FL transcript displayed in orange. b Principal Component analysis (PCA) plot of all brain samples from GTEx project and TCGA samples using gene expression from 20,214 genes from hg19. Samples are colored based on status of predominant NTRK2 transcript: teal for TrkB.T1 and orange for TrkB.FL. Normal brain regions are displayed as circles, brain tumors are displayed as triangles. c TrkB.T1 and TrkB.FL transcript expression shows increased expression of TrkB.T1 compared with TrkB.FL across 50 human glioblastoma stem cell (GSC) lines (6 lines: BTSC349, BTSC349, h543, h516, h561, h676; 44 lines from ref. ³¹) (n = 50 for each isoform (TrkB.T1 and TrkB.FL); t-test, p = 1.9 × 10⁻⁰⁸). For a and c, data are represented as boxplots where the middle line is the median, the lower and upper hinges correspond to the first and third quartiles (the 25th and 75th percentiles), the upper whisker extends from the hinge to the largest value no further than 1.5 * IQR from the hinge (where IQR is the inter-quartile range, or distance between the first and third quartiles) and the lower whisker extends from the hinge to the smallest value at most 1.5 * IQR of the hinge while data beyond the end of the whiskers are outlying points that are plotted individually⁸⁵.