Apoptosis is related to many diseases and development. Mitochondrial proteins, such as cytochrome c, Apaf-1, and AIF play important role in apoptosis. A novel mitochondrial septin-like protein was identified recently and designated ARTS for apoptosis related protein in TGF-beta signaling pathway. ARTS that is encoded by the human septin H5/PNUTL2/CDCrel2b gene is located to mitochondria and translocates to the nucleus when apoptosis occurs. ARTS is expressed in many tissues. It enhances cell death induced by TGF-beta and, to a lesser extent, by other apoptotic agents, such as TNF-α and Fas ligand.