Mcl1-IN-4 is primarily utilized in the field of cancer research, particularly in the study of apoptosis, or programmed cell death. It functions as a potent inhibitor of Mcl1, a protein that plays a crucial role in preventing apoptosis in cancer cells. By inhibiting Mcl1, this compound helps to promote the death of cancer cells, making it a valuable tool in understanding and developing treatments for various types of cancers, including those resistant to conventional therapies. Its application extends to preclinical studies where it is used to evaluate the efficacy of targeting Mcl1 in different cancer models, aiding in the identification of potential therapeutic strategies.