Acts as transcriptional coactivator for TFAP2/AP-2. Enhances estrogen-dependent transactivation mediated by estrogen receptors. May function as an inhibitor of transactivation by HIF1A by disrupting HIF1A interaction with CREBBP. May be involved in regulation of gene expression during development and differentiation of blood cells, endothelial cells and mammary epithelial cells. Interacts via its C-terminal region with the CH1 domain of CREBBP and EP300. Interacts with all TFAP2/AP-2 isoforms. Strongly expressed in heart, spleen and testis, and weakly in liver and kidney. Undetectable in nulliparous mammary glands but strongly expressed in 11.5 dpc pregnant mammary glands. Strong expression continued until the end of the lactacting stage and then rapidly diminished during the weaning stage. Belongs to the CITED family.