Plays a highly specific role in the last step of keratinocyte differentiation. May have an essential function in lipid metabolism of the most differentiated epidermal layers. Highly expressed in the epidermis in the granular keratinocytes. Also detected in other tissues, although at much lower levels, including lung and spleen. Up-regulated during epidermal differentiation. The disease is caused by variants affecting the gene represented in this entry. Belongs to the AB hydrolase superfamily. Lipase family.