Apoptosis plays an important role in many cellular processes. In mice, the death inducer obliterator 1 (Dio1) gene, a putative transcription factor, is upregulated by apoptotic signals and encodes a cytoplasmic protein that translocates to the nucleus upon apoptotic signal activation. Dio1 expression is upregulated when an apoptosis is detected. When overexpressed, the mouse protein induced apoptosis in cell lines growing in vitro. Human DATF1 (death associated transcription factor 1) is similar to the mouse gene and therefore is thought to be involved in apoptosis.