Non-apoptotic caspase which is involved in epidermal differentiation. Seems to play a role in keratinocyte differentiation and is required for cornification (PubMed:18156206). Regulates maturation of the epidermis by proteolytically processing filaggrin (PubMed:21654840). In vitro is equally active on the synthetic caspase substrates WEHD-ACF and IETD-AFC. Involved in processing of prosaposin in the epidermis (PubMed:24872419). May be involved in retinal pigment epithelium cell barrier function (By similarity). Heterodimer of a large and a small subunit, both processed from the precursor; the mature active form is a p17/p10 dimer and the intermediate form a p20/p8 dimer. Embryo, adult liver and less in adult brain and kidney. Expressed in differentiating keratinocytes of embryonic skin (at protein level). Expressed in keratinocytes of adult skin suprabasal layers (at protein level). Expressed at embryonic day 18 specifically in cornified epithelium in the suprabasal layers. Maturation by proteolytic processing appears to be a two-step process. The precursor is processed by KLK7 to yield the p20/p8 intermediate form which acts the precursor to yield the p17/p10 mature form (By similarity). Initially it was reported that cleavage by granzyme B, caspase-8 and -10 generates the two active subunits, however the physiological relevance has not been established (PubMed:9823333). Mice show a shiny and lichenified skin with an epidermis containing more alveolar keratohyalin F-granules and an altered profilaggrin processing. The skin is highly sensitive to the formation of cyclobutane pyrimidine dimers after UVB irradiation, leading to increased levels of UVB-induced apoptosis (PubMed:17515931). Mice accumulate incomplete filaggrin breakdown products within the epidermal stratum corneum (SC), leading to reduced levels of natural moisturizing factors (NMFs) and lower SC hydration (PubMed:21654840). Belongs to the peptidase C14A family.