Used primarily as a selective and reversible proteasome inhibitor in biochemical and cellular research. It effectively blocks the degradation of ubiquitinated proteins, making it a valuable tool for studying protein turnover, apoptosis, and the role of the ubiquitin-proteasome system in various cellular processes. Commonly applied in studies related to cancer, neurodegenerative diseases, and inflammation, where abnormal protein accumulation plays a key role. Also used to induce endoplasmic reticulum stress and to investigate unfolded protein response pathways. Its cell-permeable nature allows for efficient use in cell culture experiments.