Furthermore, Nodal, a protein playing a role in the activation of the differentiation process of embryonic tissues and neural development during embryogenesis (146), has been shown to influence the expression of NGF, BDNF, GDNF, and MMP-9, resulting in the enhancement of pancreatic cancer cell invasion ability, dorsal root ganglia (DRG) and synapse outgrowth, and hence the promotion of PNI (130). Here, NGF is linked to pancreatic neoplasm.