Interestingly, Elyaman et al. (2009) found that the suppressive activity of Treg cells from IL-9R−/− mice exhibited a defect in comparison to their counterparts from WT mice, suggesting that IL-9/IL-9R pathway might have a protective role in SLE (Leng et al., 2012). The gene discussed is IL9R; the disease is systemic lupus erythematosus.