CC3 (HTATIP2) is a member of the short-chain dehydrogenases/reductases (SDR) family. It is a novel serine/threonine kinase that phosphorylates the C-terminal domain (CTD) of the largest RNA polymerase II subunit and induces the expression of apoptosis related genes Bad and Siva, as well as metastasis suppressor NM23-H2. It also interacts with an estrogen receptor alpha-interacting coactivator CIA and regulates ERalpha-mediated c-myc transcription.