Ciliobrevin D is a small molecule inhibitor that targets cytoplasmic dynein, a motor protein involved in intracellular transport along microtubules. It is primarily used in research settings to study dynein-dependent cellular processes. By inhibiting dynein's ATPase activity, Ciliobrevin D disrupts the movement of organelles, vesicles, and mitotic spindles within cells. This makes it a valuable tool for investigating cell division, intracellular trafficking, and cilia-related functions. One key application is in developmental biology and cell signaling research, where it helps elucidate the role of primary cilia in signal transduction pathways such as Hedgehog signaling. By blocking dynein-mediated retrograde transport in cilia, Ciliobrevin D can reversibly inhibit ciliary resorption and modulate signaling activity, allowing researchers to probe cilia function in real time. Due to its reversible and specific mode of action, Ciliobrevin D is also used in live-cell imaging experiments to observe the dynamic consequences of acute dynein inhibition without permanent genetic manipulation. However, it is not used therapeutically and remains strictly a research compound.