KEGG pathway analysis also revealed that FPN1 was associated with immune response-related terms, such as Th17 cell differentiation, inflammatory bowel disease, Th1 and Th2 cell differentiation, the intestinal immune network for IgA production in LUAD and Staphylococcus aureus infection, the intestinal immune network for IgA production, the chemokine signaling pathway, Fc gamma R-mediated phagocytosis, and epithelial cell signaling in Helicobacter pylori infection in LUSC (Figure 6C, 6D). This evidence concerns the gene SLC40A1 and inflammatory bowel disease.