Emerging data clearly indicate that different molecular mechanisms are involved in the pathogenesis of the various pituitary tumor subtypes, and PTTG may be increased in somatotropinomas and other pituitary tumors, but not in dopamine resistant in comparison to dopamine sensitive prolactinomas, and it is not regulated by dopamine in different experimental prolactinomas. Here, PTTG1 is linked to growth hormone-producing pituitary gland neoplasm.