CDK8 and breast cancer: Conclusions were that CHD4 coactivates HIF to promote breast tumor growth, and that different mRNAs were also up-regulated in human breast tumors (ZMYND8, KDM4C (JMJD2C), CDK8, CREBBP (CBP), KAT), suggesting the heterogeneity of epigenetic regulation of HIF in breast cancer.