ITGA4 and rheumatoid arthritis: For example, drugs such as natalizumab and basiliximab that target the proteins encoded by ITGA4 and IL21R, respectively, are currently approved or under study for the treatment of immune-mediated diseases including rheumatoid arthritis (Chiu and Ritchlin, 2017), Crohn's disease (Rutgeerts et al., 2009), and multiple sclerosis (Baldassari and Rose, 2017) or as an immune suppressor to avoid kidney transplant rejection.