SUMO modification is involved in several cellular processes such as signal transduction, cell division, and regulation of protein subcellular localization, specifically including Ras signaling and protein nuclear import/export. Previous studies have demonstrated that 14-3-3ζ, which is thought to have functions in both the nucleus and cytoplasm, is a SUMOylated protein and is required for Ras signaling. I have therefore sought to determine whether or not the SUMOylation of 14-3-3ζ promotes or inhibits its localization to the nucleus. Subcellular fractionation experiments fail to reveal a detectable change in the overall ratio of nuclear to cytoplasmic 14-3-3ζ upon knockdown of SUMO by RNAi in cultured Drosophila cells. However, immunofluorescence studies suggest that nuclear localization of this protein may increase in a subset of the SUMO knockdown cells.