DEK is a crucial mammalian nuclear phosphoprotein involved in various cellular processes, including transcriptional regulation, mRNA processing, and chromatin remodeling, which are essential for maintaining cellular homeostasis and gene expression. DEK plays a significant role in the structural organization of chromatin, influencing DNA topology and accessibility, which is vital for proper gene regulation and cellular response to environmental signals. DEK is abundant in the nucleus and interacts with several other proteins, including transcription factors and chromatin remodelers, thereby modulating their activity and stability. DEK has been associated with various clinical conditions, including autoimmune diseases and cancers, highlighting its importance in both health and disease.