UMI-77 is a small molecule inhibitor that selectively targets the Bcl-2 family protein Mcl-1 (Myeloid cell leukemia 1). Its primary application lies in cancer research, particularly in studies focused on overcoming apoptosis resistance in tumor cells. Mcl-1 is often overexpressed in various cancers, including leukemia, lymphoma, and solid tumors, where it promotes cell survival by inhibiting programmed cell death. UMI-77 binds to the hydrophobic groove of Mcl-1, disrupting its interaction with pro-apoptotic proteins like Bak and Bax, thereby restoring the cell’s ability to undergo apoptosis. Due to its specificity, UMI-77 is widely used as a research tool to probe Mcl-1-dependent survival pathways and to evaluate the therapeutic potential of Mcl-1 inhibition. It has shown cytotoxic effects in Mcl-1-dependent cancer cell lines and is often tested in combination with other chemotherapeutic agents to enhance tumor cell killing. While still in the preclinical stage, UMI-77 serves as a valuable lead compound for developing targeted therapies against cancers reliant on Mcl-1 for survival.