NTRK1 and cancer: To confirm this finding we surveyed the data available at the Broad-Novartis Cancer Cell Line Encyclopedia (CCLE, http://www.broadinstitute.org/ccle/home) and found that the log2 mRNA levels of TrkA are indeed quite low (median log2 = 3.8; CI: 3.8–4.0), although a fraction of these cells lines show gain or amplification of the TrkA locus (Additional file 1: Table S5).