– Peptidylarginine deiminase type4 (PADI4) was firstly identified as a non-MHC RA genetic risk factor. Furthermore, PADI4 risk allele possessed the association with bone damage regardless of anti citrullinated peptide antibody (ACPA) positivity in Asian RA patients. PADI4 gene codes PAD4 protein which has post-translational modification activity (citrullination). Padi4 is mainly expressed in myeloid cells and granulocytes. PADI4 Protein (Primary Amine Labeling), Human, Recombinant (His), Biotinylated is expressed in E. coli expression system with N-His tag. The predicted molecular weight is 76.6 kDa and the accession number is Q9UM07.