Elk-1 (ETS domain-containing protein Elk-1) is a transcription activator. Elk-1 is classified as a ternary complex factor (TCF), a subclass of the ETS family, which is characterized by a common protein domain that regulates DNA binding to target sequences. Elk-1 plays important roles in various contexts, including long-term memory formation, drug addiction, Alzheimer’s disease, Down syndrome, breast cancer and depression. Phosphorylation of Elk-1 has also been implicated in synaptic plasticity in the adult hippocampus.