TNF and psoriasis: Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis identified four psoriasis-related pathways, including MAPK signaling pathway (ranked 8th), IL-17 signaling pathway (ranked 9th), TNF signaling pathway (ranked 14th), and HIF-1 (hypoxia-inducible factor 1) signaling pathway (ranked 16th) (Figure 2D).