RET and cancer: In addition, neurons and their related SCs can also release soluble GFRα1 and GDNF(secreted by nerve macrophages), strongly activate RET in cancer cells and initiate the downstream activation of RAS/ERK, MAPK, JNK, and PI3-K-AKT signaling pathways, cancer cell migration, and PNI effect, and induced migration along the nerve [33,42,114,116,117].