WEHI-539 is primarily utilized in biochemical and pharmacological research due to its role as a selective inhibitor of BCL-XL, a protein involved in regulating apoptosis (programmed cell death). Its application is significant in studying cancer biology, as BCL-XL is often overexpressed in various cancers, contributing to tumor survival and resistance to chemotherapy. By inhibiting BCL-XL, researchers can explore mechanisms to induce apoptosis in cancer cells, potentially leading to the development of targeted cancer therapies. Additionally, it is used to investigate the role of BCL-XL in other diseases where apoptosis regulation is disrupted, such as neurodegenerative disorders. Its use in laboratory settings helps in understanding cellular pathways and evaluating the efficacy of potential therapeutic agents.