IEX-1 is a stress inducible gene that is induced by ionizing radiation, ultraviolet radiation, and a variety of growth factors, i.e., FAS and TNF-α. IEX-1 is widely expressed in epithelial and endocrine tissues, as well as in vascular endothelium. It plays an important role in the regulation of cellular growth, cell death and oncogenesis. IEX-1 is precisely regulated by multiple transcription factors such as p53, NF-κB/rel, Sp1 and c-Myc, to ensure rapid and transient expression of IEX-1 in cells under a variety of stress conditions. IEX-1 is expressed as both a longer form (IEX1L) and a splice variant, designated IEX1S. It is localized to the nucleus and perinuclear region. Overexpression of IEX-1 facilitates apoptosis and cell cycle progression, whereas disruption of IEX-1 expression is associated with decreases in both apoptosis and cell cycle progression.
