HTATIP2 is part of the short-chain dehydrogenases/reductases(SDR) family which acts as a tumor suppressor in metabolic suppression, inhibition of angiogenesis and induces the expression of apoptosis related genes Bad and Siva. HTATIP2 cooperates with the activation domain of HIV-1 TAT and enhances its transcription by phosphorylating RNA polymerase II(Pol II). Defects in HTATIP2 are related with hepatocellular carcinomas and apoptotic resistant tumor cells, implicating a probable use for HTATIP2 in antitumor therapy.