NTRK1 and pancreatic neoplasm: A positive correlation was observed among the expression levels of NGF, p75NTR, TRKA, TRKB, glial cell line-derived neurotrophic factor (GDNF), and PNI in pancreatic cancer tissues or cell lines (Sclabas et al., 2005; Ma et al., 2008; Wang et al., 2009).