Serum response factor
Serum response factor, also known as SRF, is a transcription factor protein.

# Function
Gene ID: 6722 SRF serum response factor, "This gene encodes a ubiquitous nuclear protein that stimulates both cell proliferation and differentiation. It is a member of the MADS (MCM1, Agamous, Deficiens, and SRF) box superfamily of transcription factors. This protein binds to the serum response element (SRE) in the promoter region of target genes. This protein regulates the activity of many immediate-early genes, for example c-fos, and thereby participates in cell cycle regulation, apoptosis, cell growth, and cell differentiation. This gene is the downstream target of many pathways; for example, the mitogen-activated protein kinase pathway (MAPK) that acts through the ternary complex factors (TCFs). Two transcript variants encoding different isoforms have been found for this gene."
- NP_003122.1 serum response factor isoform 1: "This variant (1) represents the longer transcript and encodes the longer isoform (1)." cd00266 (Location:142  223): "MADS_SRF_like; SRF-like/Type I subfamily of MADS (MCM1, Agamous, Deficiens, and SRF (serum response factor) box family of eukaryotic transcriptional regulators. Binds DNA and exists as hetero- and homo-dimers. Differs from the MEF-like/Type II subgroup mainly in position of the alpha 2 helix responsible for the dimerization interface. Important in homeotic regulation in plants and in immediate-early development in animals. Also found in fungi."
- NP_001278930.1 serum response factor isoform 2: "This variant (2) differs in the 5' UTR and coding sequence compared to variant 1. The resulting isoform (2) is shorter at the N-terminus compared to isoform 1."
Serum response factor is a member of the MADS (MCM1, Agamous, Deficiens, and SRF) box superfamily of transcription factors. This protein binds to the serum response element (SRE) in the promoter region of target genes. This protein regulates the activity of many immediate early genes, for example c-fos, and thereby participates in cell cycle regulation, apoptosis, cell growth, and cell differentiation. This gene is the downstream target of many pathways; for example, the mitogen-activated protein kinase pathway (MAPK) that acts through the ternary complex factors (TCFs).
SRF is important during the development of the embryo, as it has been linked to the formation of mesoderm. In the fully developed mammal, SRF is crucial for the growth of skeletal muscle. Interaction of SRF with other proteins, such as steroid hormone receptors, may contribute to regulation of muscle growth by steroids. Interaction of SRF with other proteins such as myocardin or Elk-1 may enhance or suppress expression of genes important for growth of vascular smooth muscle.

# Transcriptions
"A common feature of many muscle genes is their dependence on a cis-acting sequence known as a CArG box (CC(A/T)6GG), which serves as the binding site for serum response factor (SRF) (reviewed in Shore and Sharrocks, 1995)."

# Interactions
Serum response factor has been shown to interact with:
- ASCC3,
- ATF6,
- CEBPB,
- CREB-binding protein,
- ELK4,
- GATA4,
- GTF2F1,
- GTF2I,
- Myogenin,
- NFYA,
- Nuclear receptor co-repressor 2,
- Promyelocytic leukemia protein and
- Src,  and
- TEAD1.

# Clinical significance
Lack of skin SRF is associated with psoriasis and other skin diseases.