Potent, cell permeable and selective, reversible proteasome inhibitor. Blocks degradation of short-lived proteins and induces a heat shock response. NF-kappaB activation inhibitor through IkappaB degradation. Cell permeable, reversible peptide aldehyde inhibitor. Calpain and cathepsin inhibitor. Has anticancer properties by inducing cell cycle arrest and activating apoptosis in various cancer cell lines. Has adjuvant/chemosensitizer potential. Neurite outgrowth stimulator in PC12 cells. Prevents beta-secretase cleavage. Autophagy activator.