While some studies have shown GALR2 to be proproliferative [49], others indicate that reintroduction of GALR2 into tumor cell lines established from pheochromocytoma, neuroblastoma and HNSCC are susceptible to galanin-mediated apoptosis and/or growth inhibition [50,51,52]. This evidence concerns the gene GALR2 and head and neck squamous cell carcinoma.