Lyn peptide inhibitor is primarily used in research settings to study and understand signaling pathways in cells, particularly those involving the Lyn kinase enzyme. It is employed to investigate the role of Lyn in immune cell function, especially in B cells and mast cells, where Lyn plays a critical role in regulating responses. By inhibiting Lyn, researchers can explore its impact on cell proliferation, differentiation, and survival, which is valuable in understanding diseases like cancer, autoimmune disorders, and allergic reactions. Additionally, it helps in identifying potential therapeutic targets for conditions where Lyn kinase activity is dysregulated.