Following translocation to the nucleus, ERK1/2 directly phosphorylates key effectors, including the ubiquitous transcription factors ELK1 (Ets like protein 1). At least five residues in the C terminal domain of ELK1 are phosphorylated upon stimulation with growth factor stimulation. ELK1 can form a ternary complex with the serum response factor (SRF) and consensus sequences, such as serum response elements (SRE), on DNA, thus stimulating transcription of a set of immediate early genes like FOS (c-fos) (Marais et al, 1993; Gille et al, 1995; Duan et al, 1998; reviewed in Treisman, 1995).
