SLC6A4 and depressive symptom measurement: In addition, the induction of depression- or anxiety-like behaviors by SERT deletion is closely associated with increased DNA methylation of Bdnf and decreased availability of transcription factors such as cAMP-response element-binding protein (Creb), neuronal PAS domain protein 4 (Npas4), and calcium-responsive transcription factor (Carf) (Molteni et al., 2010; Calabrese et al., 2013).