For instance, association of the severity of rheumatoid arthritis with the ability of FSTL1 to activate the signaling pathways MAPK, JAK/STAT3, and NF-kB and increase the secretion of metalloproteinases 1, 3, and 13 was shown in the article of Ni et al. [95]. This evidence concerns the gene FSTL1 and rheumatoid arthritis.