SUMO1 and Alzheimer disease: However, decreased SUMO‐2/3 levels were detected in older APP mice at 17 months of age, whereas increased levels of SUMO1, Ubc9, and SENP1 levels were observed in younger APP mice at 3 and 6 months of age.[63] These data indicates that SUMOylation contributes to the development of AD and SUMO‐1/SUMO‐2/3 have diverse functions in the pathogenesis of AD in a course‐dependent manner.