NPBWR1 and Anxiety: However, in the open-field test, Npbwr1−/− mice exhibited no abnormality in the percentage of time spent in the center of the arena (thigmotaxis), and showed no significant difference in the percentage of time spent in the open arms in the elevated-plus maze test (Fig. 2C), suggesting that the basal level of anxiety was unaltered in Npbwr1−/− mice.