ζ-Stat trisodium is primarily used in research settings to study cellular signaling pathways, particularly those involving the JAK-STAT pathway. It serves as an inhibitor, helping scientists understand the role of STAT proteins in various biological processes, including immune responses, cell growth, and cancer development. Its application extends to preclinical studies where it aids in evaluating potential therapeutic targets for diseases linked to abnormal STAT activation, such as autoimmune disorders and certain cancers. Additionally, it is utilized in biochemical assays to dissect the molecular mechanisms of STAT phosphorylation and dimerization, providing insights into signal transduction.