IL-4 and IL-13 have partly shared receptor systems. IL-4 binds IL-4Rα/γC in lymphocytes and other hematopoietic cells, activates the JAK1/JAK3-STAT6 pathway, and induces Th2 differentiation and IgE production. IL-4 and IL-13 share IL-4Rα/IL-13Rα1 in keratinocytes, activate the JAK1/JAK2/TYK2-STAT6 and -STAT3 pathway, and inhibit the expression of EDC molecules such as FLG, LOR, and IVL. IL-4 and IL-13 also inhibit the cytoplasmic-to-nuclear translocation of OVOL1 and downregulate the expression of FLG and LOR. IL-4/IL-13-mediated STAT6 activation upregulates periostin and subsequently enhances IL-24 production. IL-24 binds to IL-20Rβ/IL-22Rα or IL-20Rβ/IL-20Rα, activates the JAK1/TYK2-STAT3 pathway, and inhibits the expression of FLG.