EZH2 and parathyroid hyperplasia: In addition, the EZH2 gene amplification, with consequent over-expression of the EZH2 protein, contributing to the aberrant accumulation of active β-catenin in the nucleus and resulting in increased cell proliferation, is a common event in parathyroid hyperplasia, adenomas, and carcinomas, confirming a role of the enhanced expression of this gene as a pro-oncogenic factor in parathyroid cells [45].