MX1013 is a potent, irreversible dipeptide caspase inhibitor vith antiapoptotic activity. MX1013 inhibits recombinant human caspase 3 with an IC 50 of 30 nM In Vitro MX1013 inhibits caspases 1, 3, 6, 7, 8, and 9, with IC 50 values ranging from 5 to 20 nm. MX1013 is selective for caspases, and is a poor inhibitor of noncaspase proteases, such as cathepsin B, calpain I, or Factor Xa (IC 50 values >10 μm). MX1013 inhibits three key markers of apoptosis: the proteolytic maturation of caspase 3, the caspase-mediated cleavage of PARP, and the fragmentation of genomic DNA. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Cell Proliferation AssayCell Line: Jurkat T-lymphocytes Concentration: 0, 0.05, 0.1, 0.25, 0.5 μM Incubation Time: Preincubated for 2 h Result: Neither caspase 3 processing nor PARP cleavage could be detected at 0.5 μM. At concentrations of 0.05 μM, caspase 3 processing and PARP cleavage were still markedly reduced. In Vivo MX1013 is an effective antiapoptotic agent in vivo. MX1013 not only inhibits local tissue apoptosis, but also can protect animals against its lethal effects . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: Female ND4 Swiss Webster mice (16.5-21 g) Dosage: 0, 0.25, 1, 10 mg/kg (formulated in an aqueous vehicle containing 50 mm Tris-HCl, pH 8.0) Administration: Injected i.v. Result: The lowest dose of 0.25 mg/kg protected 66% of the mice from the lethal effects of anti-Fas antibody at the 3 h time point, and 1 and 10 mg/kg dose protected 100% of the mice at the 3 h time point. Form:Solid IC50& Target:Caspase