The DEK oncogene is an approximately 45 kDa phosphoprotein with pleiotropic activities. It is a chromatin remodeling factor, a transcriptional coactivator and corepressor, a component of RNA spliceosomes, and a promoter of DNA repair during apoptosis. DEK is upregulated in many cancers and promotes epithelial cell transformation. It functions as a proinflammatory factor when secreted by activated macrophages. It is an autoantigen in juvenile arthritis and lupus and a target of chromosomal translocation with the CAN gene in acute myelogenous leukemia. DEK contains one SAP domain (aa 149-183), one nuclear localization sequence (aa 205-221), and a DNA-binding C-terminal domain (aa 321-375).