A synthetic tripeptide aldehyde that acts as a potent inhibitor of cysteine proteases including calpain I (Ki = 190 nM), calpain II (Ki = 220 nM) cathepsin B (Ki = 150 nM), and cathepsin L (Ki = 500 pM); prevents the degradation of IκBα and IκBβ by the ubiquitin-proteasome complex, which blocks activation of NFκB and the production of TNF and IL-1β