Members of the SMAD family of signal transduction molecules are components of key intracellular pathways,[25] and Smad3 forms a complex with Smad4 after phosphorylation at its carboxyl terminus and translocases to the nucleus to regulate gene expression.[26] Compared with that of the PTSD group, the phosphorylation level of Smad3 in the cerebral prefrontal cortex of mice in the TBI+PTSD group was significantly increased (Figure 4H), and the expression of Smad3 (S423 + S425) was also significantly increased in the cytoplasm/nucleus (Figure 4I). The gene discussed is SMAD4; the disease is post-traumatic stress disorder.