SSTR2 and pituitary gland adenoma: While SSTR3 is expressed in most pituitary adenomas, independent of the functional type, SSTR5 and SSTR2 (SSTR5 more than SSTR2) are widely expressed in somatotroph, thyrotroph, corticotroph, lactotroph, and gonadotroph adenomas and are probably involved in the regulation of hormonal secretion [22].