We found that, compared to WT, Mapt−/− mice are resistant to depression-like behavior, as evidenced by a significant decreased immobility in the tail suspension (Figure 1A; p < 0.001) and forced swim (Figure 1B; p < 0.05) tests, as well as decreased failures and latency to escape in the learned helplessness task (Figure 1C,D; p < 0.05). The gene discussed is MAPT; the disease is major depressive disorder.