GPER1 and hereditary pheochromocytoma-paraganglioma: Among the 31 tumour entities investigated in the present study, notable GPER expression (mean IRS value ≥ 3) was only observed in hepatocellular, pancreatic, and renal clear cell carcinomas, pancreatic neuroendocrine tumours, pheochromocytomas, and endometrial cancer.