PADI4 and rheumatoid arthritis: Remarkably, PADI2 and PADI4 had distinct as well as overlapping substrates, for example, PADI4 directly citrullinates nuclear factor κB (NF-κB) p65 to promote its nuclear localization and transcriptional activity of key immune genes including IL-1β and tumor necrosis factor α (TNFα) to propagates inflammation in rheumatoid arthritis [42], whereas, mice with TNFα-induced inflammatory arthritis showed that PADI2 contributes to TNFα-induced citrullination, but not required for NETosis.