This might be due to 1) CDC42 knockdown could mediate a trafficking/functionality defect in γ-aminobutyric acid type B receptors, resulting in anxiety and depression (23); or 2) CDC42 knockdown might promote the synthesis of xanthine by regulating the differentiation of CD4+ T cells, thus leading to anxiety, depression, and other behaviors (10). Here, CD4 is linked to major depressive disorder.