The results showed that PEG ointment could down-regulate the mRNA levels of genes IL-23, IL-17C, IL-17F, IL-22, S100A7, S100A8, S100A9, CXCL1, CXCL2, CXCL3, IL-1β, and IL-6 induced by the psoriasis mouse model (Figure 5). This evidence concerns the gene S100A9 and psoriasis.