Unexpectedly, as a classical co-receptor of the GFRA1 protein, the RET protein and its coding gene were basically not expressed in the multiple GC cell lines tested, and their expression levels were not associated with GC liver metastasis, suggesting that GFRA1 may promote GC liver metastasis through a nonclassical RET-independent pathway (Fig. 2A, S1A). The gene discussed is RET; the disease is gastric cancer.