Suppressesapoptosisinavarietyofcellsystemsincludingfactor-dependentlymphohematopoieticandneuralcells.Regulatescelldeathbycontrollingthemitochondrialmembraneperme
ABIlity.Appearstofunctioninafeedbackloopsystemwithcaspases.Inhibitscaspaseactivityeitherbypreventingthereleaseofcytochromecfromthemitochondriaand/orbybindingtotheapoptosis-activatingfactor(APAF-1).