<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Any substance that inhibits glutamate-cysteine ligase (gamma-glutamylcysteine synthetase), an enzyme that catalyzes the ATP-dependent condensation of cysteine and glutamate to form the dipeptide gamma-glutamylcysteine, the rate-limiting step in the biosynthesis of glutathione. Since glutathione is critical in protecting cells against oxidative stress, its depletion results in free radical-induced apoptosis.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>