ML-9 is primarily used in biochemical research as a selective inhibitor of myosin light chain kinase (MLCK). It is utilized to study the role of MLCK in various cellular processes, particularly in smooth muscle contraction and cytoskeletal organization. Researchers employ ML-9 to investigate signaling pathways involved in cell motility, endothelial barrier function, and vascular tone regulation. Its application extends to understanding the mechanisms underlying diseases such as hypertension, asthma, and cancer metastasis, where MLCK activity plays a critical role. Additionally, ML-9 is a valuable tool in pharmacological studies aimed at developing therapeutic agents targeting MLCK-related pathways.