On the one hand, GFRα1 was identified as a target protein of ST3 beta-galactoside alpha-2,3-sialyltransferase 1 (ST3GAL1), which regulates the GDNF/GFRα1/RET pathway in breast cancer cells by mediating O-linked sialylation of GFRα1 and facilitating its interaction with RET. Here, GDNF is linked to breast cancer.