PADI2 and rheumatoid arthritis: Further studies to elucidate the role of Padi2 in both stem cells and endothelial cells may provide valuable new information in understanding the genetic heterogeneity of angiogenic responsiveness and how this heterogeneity correlates with the susceptibility to angiogenesis-dependent diseases such as cancer, multiple sclerosis, rheumatoid arthritis, and macular degeneration.