GPR68 and neuroendocrine neoplasm: If only gastroenteropancreatic neuroendocrine tumours were included in the analysis, significantly higher GPR68 levels were again noted in patients without lymph node metastases (without lymph node metastases: 2.473 ± 0.512; with lymph node metastases: 1.449 ± 0.238; Mann–Whitney test: p = 0.012).