GPR19 and medullary thyroid gland carcinoma: Regarding the different tumour types, GPR19 was predominantly expressed in adenocarcinomas of the lung and lung tumours with a neuroendocrine background, and, to a lesser extent, in other neuroendocrine tumour entities such as medullary thyroid carcinomas, parathyroid adenomas, pheochromocytomas, and pancreatic neuroendocrine neoplasms.