NTRK1 and pancreatic neuroendocrine tumor: For example, C-X-C chemokine receptor type 4 (CXCR4) expression increases with G3 tumors (Kaemmerer et al. 2015) and tyrosine kinase receptors c-KIT as well as platelet derived growth factor receptor alpha (PDGFRα) were reported to be a negative prognostic marker in pancreatic NET (Knösel et al. 2012).