Their potential importance in the biology of the epidermal stratified squamous epithelium and barrier function is consistent with: (1) in vitro studies using reconstituted human epithelium (Sa et al., 2007); (2) their high expression in human skin and esophagus [National Library of Medicine (US), 1988]; and (3) the human genome analyses that link them to functions in psoriasis, inflammatory bowel disease, suppression of melanoma (IL-24 only) (GeneCards®: The Human Gene Database, 2022) and regulation of epidermal inflammation (Jin et al., 2014). Here, IL24 is linked to psoriasis.