GAL and head and neck squamous cell carcinoma: Galanin (GAL) stimulates a variety of signal transduction and integration pathways by activating its receptors GALR1, GALR2, and GALR3,14, 15 and thus far, GALRs have been found to be the most effective markers for predicting the prognosis of head and neck squamous cell carcinoma (HNSCC) patients.16, 17