DRD2 and adenoma: High D2R protein expression levels were found in 26 of 70 NFPT, 26 of 28 prolactinomas, and 18 of 20 GH-secreting adenomas, as well as 31 of 37 FSH-secreting adenomas, 18 of 27 ACTH-secreting adenomas, and 9 of 15 thyrotropinomas (9).