Promyelocytic leukemia protein (PML) nuclear bodies (NBs), which are sub-nuclear protein structures, are involved in a variety of important cellular functions.PML is a tumour suppressor and regulator of cell differentiation. PML-NBs are assembled by PML isoforms, and contact between small ubiquitin-like modifiers (SUMOs) with the SUMO interaction motif (SIM) are critically involved in this process. PML isoforms contain a common N-terminal region and a variable C-terminus. The PML (promyelocytic leukemia) protein is a member of the TRIM family, a large group of proteins that show high diversity in functions but possess a common tripartite motif giving the family its name. Promyelocytic leukemia (PML), which is a tumor suppressor protein that nevertheless plays an important role in the maintenance of leukemia initiating cells, is known to be biochemically modified by As(3+).