Secretion of GFLs and soluble forms of GFRα1 within the nerve, stimulates movement of RET-expressing tumor cells along a chemotactic gradient of GFLs to invade the perineural space and move along nerve fibers toward the central nervous system, an invasive process which is strongly linked to poorer patient outcomes, neuropathy and tumor-related pain (Veit et al., 2004; Zeng et al., 2008; Gil et al., 2010; Cavel et al., 2012; He et al., 2014; Amit et al., 2016). This evidence concerns the gene RET and neoplasm.