RET and neoplasm: Several studies have shown that varying levels of RET are expressed broadly on immune cells of both myeloid and lymphoid lineages, suggesting that recruitment of these cells to the tumor microenvironment may be enhanced by higher localized GFL levels, further potentiating tumor growth and invasive spread (Borrello et al., 2005; Vargas-Leal et al., 2005; Cavel et al., 2012; Gattelli et al., 2013; Rusmini et al., 2014; Ibiza et al., 2016).