PADI4 and rheumatoid arthritis: High activity of PAD4 has been associated with the appearance and progression of RA because it promotes neutrophils recruited to the site of inflammation and the formation of neoantigens, and the hypercitrullination of vimentin, fibrinogen, type II collagen, and α-enolase [4,5,6], which are the primary targets of the autoantibodies in RA.