GH1 and pituitary gland adenoma: Pituitary adenomas are categorized by secretory activity; null cell adenomas and prolactinomas (PRL) are the most common pituitary adenomas, followed by growth hormone (GH)-pituitary adenomas, adrenocorticotropic hormone (ACTH)-pituitary adenomas, follicle-stimulating hormone (FSH)-pituitary adenomas, and thyroid-stimulating hormone (TSH)-pituitary adenomas (Ezzat et al., 2004; Lake, Krook & Cruz, 2013; Melmed, 2015).