ABT-737 is primarily used in research settings to study apoptosis, or programmed cell death, in cancer cells. It functions as a potent inhibitor of Bcl-2 family proteins, which are often overexpressed in various cancers to prevent cell death. By blocking these proteins, ABT-737 promotes apoptosis in cancer cells, making it a valuable tool for understanding cancer biology and developing potential therapeutic strategies. It is also used in preclinical studies to evaluate its efficacy in combination with other anticancer agents, providing insights into synergistic effects and resistance mechanisms. Additionally, ABT-737 helps researchers explore the role of Bcl-2 family proteins in other diseases where apoptosis regulation is disrupted.