IL-17F is part of the IL-17 cytokine family which consists of at least seven structurally related proteins (IL-17A, B, C, D, E, F, and A/F). IL-17F homodimer adopts a cysteine knot motif formed through the interactions of four cysteines, one of which is responsible for inter-chain bonding. IL-17F is most closely related to IL-17A, sharing 50% amino acid sequence homology. It is expressed by Th17 cells, along with IL-17A homodimer and IL-17A/F heterodimer. IL-17F has been shown to inhibit endothelial cell angiogenesis and induce increased production of IL-2, TGF-beta, and MCP-1, playing a critical role in the regulation of inflammatory reactions.