CCK and small cell lung carcinoma: Furthermore, neuropeptides such as endothelin, bradykinin, neuromedin B, cholecystokinin and angiotensin II activate their cognate GPCRs to stimulate cell proliferation in various cell types, and play a crucial role in many aggressive human cancers, including small-cell lung cancer (SCLC), pancreatic cancer, head and neck squamous cell carcinoma (HNSCC), and prostate cancer [18], [19].