Description_x000D_ Packaging_x000D_ 5, 25 mg in glass bottle_x000D_ Biochem/physiol Actions_x000D_ RA-9 is a cell permeable and potent inhibitor of the ubiquitin-proteasome system (UPS) that targets deubiquitinating enzymes (DUB) without affecting 20S proteasome catalytic-core activity. RA-9 directly inhibits activity of following DUB UCH-L1, UCH-L3, USP2, USP5 and USP8 deubiquitinating enzymes, which results in rapid accumulation of poly-ubiquitinated proteins leading to cell cycle checkpoint arrest and tumor cell apoptosis.