WHI-P154 is primarily used in biochemical and biomedical research as a selective inhibitor of the Janus kinase 3 (JAK3) signaling pathway. It is valued for its ability to suppress JAK3-dependent cellular processes with minimal effect on related kinases, making it a useful tool for studying immune cell signaling and cytokine receptor pathways. Researchers apply WHI-P154 to investigate the role of JAK3 in lymphocyte activation and proliferation, particularly in the context of autoimmune diseases and transplant rejection. Its selectivity also supports its use in screening studies aimed at developing targeted immunomodulatory therapies. Additionally, WHI-P154 has been employed in studies exploring the STAT5 signaling cascade, helping to clarify the downstream effects of JAK3 inhibition in hematopoietic cells.