The predominant cause of feline acromegaly is a functional somatotropic adenoma in the pars distalis of the anterior pituitary gland resulting in excessive growth hormone (GH) secretion.1"3 Research into the underlying mechanism of this adenomatous change has revealed overexpression of the cell cycle gene cyclin B2 (ccnb2) in human pituitary adenomas.4 The exact initiating factor for this overexpression remains to be elucidated. In mouse models it has been shown that direct binding of so-called highmobility group A (HMGA) proteins to the promoter of the ccnb2 gene occurs during pituitary tumour formation. Additionally HMGA proteins were shown to be able to up-regulate ccnb2 promoter activity. Whether these human and mouse model findings correlate with the situation in the cat is unclear.
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