WHI-P131 is primarily used in research settings as a selective inhibitor of the JAK3 kinase enzyme. It plays a significant role in studying signal transduction pathways, particularly those involved in immune cell function and development. Researchers utilize WHI-P131 to investigate its potential in modulating immune responses, which can provide insights into treating autoimmune diseases and conditions like leukemia or lymphoma. Its application also extends to exploring its effects on T-cell and B-cell proliferation, aiding in the understanding of immune system regulation and potential therapeutic interventions.