N4BP1 is an 896 amino acid protein that belongs to the N4BP1 family. N4BP1 primarily localizes to nucleolus, however it also localizes to PML nuclear bodies when desumoylated. Detected in heart, lung, brain, liver, skeletal muscle, pancreas, kidney, spleen, testis and ovary, N4BP1 is phosphorylated upon DNA damage probably by ATM or ATR. N4BP1 interacts with Nedd4, a protein with a wide range of activities including modification of ubiquitin-protein ligase, regulation of membrane channels ａnd