Serum response factor (SRF) is a nuclear transcription factor that binds to the serum response element (SRE), and is essential for embryonic development of the mesoderm, as well as for the maintenance of adult muscle cells and neurons. As this protein is involved in the downstream regulation of many immediate-early genes, it participates in a variety of cell functions, including cell cycle, apoptosis, cell growth, and cell differentiation. SRF is most commonly activated by serum, LPA, LPS, TPA, growth factors, including TNFalpha, as well as antioxidants and UV light.