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. Author manuscript; available in PMC: 2016 Mar 1.
Published in final edited form as: Endocrinol Metab Clin North Am. 2015 Mar;44(1):1–9. doi: 10.1016/j.ecl.2014.11.004

Figure 2.

Figure 2

Pituitary adenoma signaling. Transcription of pituitary hormone genes and cell proliferation are induced by pituitary mitogenic factors including hypothalamic hormones and transcription factors, as well as peripheral hormones. Proliferative constraints include somastostatin and dopamine, as well as tumor suppressor genes. Cell cycle progression is mediated by CDK–cyclin complexes that phosphorylate Rb and cause it to release E2F, which drives cell proliferation. CDK inhibitors block kinase phosphorylation, thereby restraining cell cycle progression. Chromosomal instability, DNA damage and senescence may act to constrain malignant transformation of pituitary tumors.

From Melmed S 2009 Acromegaly pathogenesis and treatment. J Clin Invest 119:3189-3202, with permission.