Targeted disruption of caspase genes in mice: What they tell us about the functions of individual caspases in apoptosis

Cysteine proteases of the caspase family are crucial mediators of apoptosis . All mammalian cells contain a large number of caspases. Although many cas pases are activated in a cell committed to apoptosis, recent data from casp ase gene knockout mice suggest that individual caspases may be involved in the cell and Stimulus-specific pathways of cell death. The gene disruption studies also establish the functional hierarchy between two structurally di stinct classes of caspases. The present review discusses these recent findi ngs and elaborates on how these mutant mouse models have helped the underst anding of the mechanisms that govern programmed cell death in the immune an d other systems.