NTRK1 and cancer: Strikingly, downregulation of NTRK1 encoding tropomyosin receptor kinase A (TRKA), a high affinity receptor for nerve growth factor (NGF), was most prominently associated with three KEGG pathways, namely 'transcriptional misregulation in cancer', 'Pathways in cancer' and the 'MAPK signaling pathway' (Figure 3C).