By looking at The Cancer Genome Atlas (TCGA) data available through the cBioPortal (http://www.cbioportal.org/index.do; ref. [30, 31]), the TrkA gene is recurrently altered (14 % of 278 reported tumor samples with RNA-seq and CNA data) in MM, via amplification, mRNA level upregulation, and missense mutations (Additional file 2: Figure S2A). This evidence concerns the gene NTRK1 and neoplasm.