HTATIP2, also known as TIP30, is a member of the short-chain dehydrogenases/reductases (SDR) family. It acts as a tumor suppressor participating in metabolic suppression, inhibition of angiogenesis and induces the expression of apoptosis related genes Bad and Siva. HTATIP2 interacts with the activation domain of HIV-1 TAT and enhances its transcription by phosphorylating RNA polymerase II (Pol II). Defects in This protein are associated with hepatocellular carcinomas and apoptotic resistant tumor cells, suggesting a potential use for HTATIP2 in antitumor therapy.