Proteasome inhibitor; inhibits chymotrypsin-like activity of the proteasome. Causes dopaminergic cell death in vitro. Prevents activation of NF-κB in response to TNF-α and okadaic acid (Cat. No. 1136) by inhibiting IκB-α degradation. Also inhibits NO production by LPS-activated macrophages. Purity 90%. MW (observed): 618.77