Injection of blood–brain barrier-permeable TAT-DEF-ELK-1 (TDE) peptide, which disrupts ERK-mediated ELK-1 phosphorylation (activation) in the DG, improved behavioral signs in the depression models and in mice overexpressing ELK-1, without affecting basal levels of locomotion and memory (Lavaur et al., 2007; Apazoglou et al., 2018). This evidence concerns the gene ELK1 and depressive symptom measurement.