MI-3 is a potent inhibitor targeting the interaction between menin and the mixed lineage leukemia (MLL) protein. This interaction plays a critical role in the development of certain leukemias, particularly MLL-rearranged leukemia, a highly aggressive form of acute leukemia. By disrupting this protein-protein interaction, MI-3 effectively suppresses the oncogenic gene expression programs driven by MLL fusion proteins. The compound is primarily used in research settings to study leukemia cell biology and to evaluate the therapeutic potential of menin-MLL inhibition. It has demonstrated strong anti-leukemic activity in vitro and in preclinical models, including reduced proliferation and induction of apoptosis in leukemia cell lines. Its selectivity makes it a valuable tool for validating menin as a drug target and for guiding the development of clinical candidates. MI-3 also supports studies in epigenetics and transcriptional regulation, helping researchers understand how protein interactions influence gene activation in cancer. Due to its role in blocking key cancer-promoting pathways, MI-3 serves as a prototype for novel targeted therapies in hematological malignancies.