This volume explores various methodologies to study biochemical, molecular, and cellular biology aspects of some processes regulated by protein SUMOylation. SUMO: Methods and Protocols is organized into four parts, and starts with an historical overview on protein SUMOylation and a presentation of the methods included in the book. The first part also includes a review on chromatin regulation by dynamic SUMO modifications. The second part focuses on in vitro techniques, including biochemical methods to study mechanistic aspects of protein SUMOylation. The third part includes protocols to be used with cell cultures, which often are the first approaches used in most laboratories. The final part includes methodologies adapted for the analysis in vivo using distinct model organisms. Written in the highly successful Methods in Molecular Biology series format, chapters include a brief introduction to the subject, a list of necessary materials and reagents, a step-by-step reproducible laboratory protocol ending with a Notes section on troubleshooting tips, and tips and strategies to avoid known pitfalls. Unique and cutting-edge, SUMO: Methods and Protocols provides a comprehensive source of protocols for specialists and researchers not familiar with this vital system.