GREM2 and Anxiety: Males showed a more prominent effect of the lack of Grem2 on anxiety behaviors than females, with male Grem2−/− mice spending significantly more time in the closed arms than WT male mice (Fig. 4D,G,H; females, WT, 88.73% ± 2.01%; n = 17; Grem2−/−, 89.00% ± 1.89%; n = 15; p = 0.9624x; males, WT, 84.74% ± 3.23%; n = 17; Grem2−/−, 94.52% ± 1.78%; n = 15; p = 0.0193y).