Non-apoptotic caspase involved in epidermal differentiation. Is the predominant caspase in epidermal stratum corneum. Seems to play a role in keratinocyte differentiation and is required for cornification. Regulates maturation of the epidermis by proteolytically processing filaggrin. In vitro has a preference for the substrate [WY]-X-X-D motif and is active on the synthetic caspase substrate WEHD-ACF . Involved in processing of prosaposin in the epidermis. May be involved in retinal pigment epithelium cell barrier function. Involved in DNA degradation in differentiated keratinocytes probably by cleaving DFFA/ICAD leading to liberation of DFFB/CAD.