Caspases are a family of cysteine proteases that can be divided into apoptotic and inflammatory caspase subfamilies. Unlike the apoptotic caspases, members of the inflammatory subfamily are generally not involved in cell death but are associated with the immune response to microbial pathogens. Members of this subfamily include caspase-1, -4, -5, and -12 and can activate proinflammatory cytokines such as IL-1b and IL-18. Caspase-14 is highly expressed in embryonic but not adult tissues. It is processed and activated by caspase 8 and caspase 10 in vitro, and by anti-Fas agonist antibody or TNF-related apoptosis inducing ligand in vivo. The expression and processing of this caspase may be involved in the keratinocyte terminal differentiation, which is important for the formation of the skin barrier.