GPER1 and lung carcinoid tumor: Overall, based on the percentage of GPER-positive tumours (IRS ≥ 3; Figure 7A) and the extent of GPER expression (Figure 7B), GPER was most prominently expressed in neuroendocrine tumours derived from the pancreas (64.6% GPER-positive cases; median IRS value, 4.5), followed by those derived from the colon (36.4% GPER-positive cases; median IRS value, 2.8) and the rectum (6.7% positive cases; median IRS value, 0.9), as well as atypical carcinoids (22.2% GPER-positive cases; median IRS value, 1.9) and typical carcinoids of the lung (18.2% GPER-positive cases; median IRS value, 1.4).