Elk-1 is a transcription factor that binds the serum response element (SRE) and mediates gene activity in response to serum and growth factors. Elk-1 is phosphorylated by MAP kinase pathways and appears to be a direct target of activated MAP kinase. Biochemical studies indicate that Elk-1 is a good substrate for MAP kinase. The kinetics of Elk-1 phosphorylation and activation correlate with MAP kinase activity. Other studies have shown that Elk-1 (Ser383) is also a target of the stress-activated kinase SAPK/JNK.