IL-17F shares approximately 50% amino acid sequence homology with IL-17A, and both upregulate the expression of proinflammatory cytokines and chemokines via NF-κB, MAPK and C/EBP activation by binding to IL-17 receptor A (IL-17 RA) and IL-17 RC complex on target cells [36]. Here, IL17F is linked to rheumatoid arthritis.