S100A4 and rheumatoid arthritis: S100A4 is a potent trigger of inflammatory molecules, such as interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-a, and matrix metalloproteinases, which are involved in autoimmune disease developments, such as allergies, rheumatoid arthritis, systemic sclerosis, and psoriasis, etc. [35].