NTRK1 and glioblastoma: Genomic and in situ fluorescent (FISH) and chromogenic hybridization (CISH) studies in GBM have detected a profound IH in the amplification patterns of receptor tyrosine kinases (RTK) and drug target genes, such as EGFR, MET, and PDGFRA (Burford et al., 2013; Little et al., 2012; Snuderl et al., 2011; Szerlip et al., 2012).