To further establish the role of PI3K/Akt/Sp1 signaling in PAD2 expression, we inhibited PI3K/Akt signaling by wortmannin (10 nM) or Sp1 expression by shRNA (Supplementary Fig. S5 online) in RA-ILD fibroblasts. This evidence concerns the gene PADI2 and rheumatoid arthritis.