Interestingly, the proportion of CD4+Foxp3+ T cells co-expressing T-bet increased in both WT and WSX-1−/− mice during the course of malaria infection (Figure 7A, D), and significantly higher frequencies and numbers of CD4+Foxp3+T-bet+ T cells were observed in WSX-1−/− mice compared with WT mice on days 9 and 11 of infection, although cell numbers were low (Figure 7D, E). The gene discussed is FOXP3; the disease is infection.