In a B16-OVA tumor model, IL-7-treated OT-II Th9 cells were found to mount potent antitumor activity, which is suppressed in the absence of Foxo1, suggesting that Foxo1-mediated IL-9 induction is essential in mounting the potent antitumor immunity by Th9 cells (16). The gene discussed is FOXO1; the disease is neoplasm.