R406 is primarily utilized in biochemical research as a selective inhibitor of spleen tyrosine kinase (Syk). It plays a significant role in studying signaling pathways in immune cells, particularly in B cells and mast cells. Researchers use R406 to investigate its effects on inflammation, allergic responses, and autoimmune diseases. Its ability to inhibit Syk makes it a valuable tool in understanding mechanisms related to immune regulation and developing potential therapeutic strategies for conditions like rheumatoid arthritis and chronic lymphocytic leukemia. Additionally, R406 is employed in preclinical studies to evaluate its efficacy and safety in modulating immune responses.