Rabbit Polyclonal Antibody to c-FOS (cFos, Fos, AP-1) Cat# RPCA-c-FOS

      The FOS gene and protein were originally identified as the transforming element in a viral oncogene. The transforming protein was named v-FOS, for viral FOS, and the normal cellular non-transforming proto-oncogene was called c-FOS, for cellular FOS. The c-Fos protein is also known as cFOS, AP-1, C-p55, Fos proto-oncogene and AP-1 transcription factor subunit. FOS is an acronym for "FBJ murine osteogenic sarcoma", the virus in which the gene product was first discovered. The c-FOS protein is a normal gene acting as an on/off switch controlling the expression of many other genes. The v-FOS form is mutated to stay in the on position, this persistently activating other genes and promoting unregulated cell division. The unmutated c-FOS is an "immediate-early" gene, so-called because protein expression is usually very low but increases rapidly and transiently in response to a wide array of stimuli including serum, growth factors, tumor promoters, cytokines, and UV radiation. Newly expressed c-FOS protein associates with JUN family and other basic leucine-zipper (bZIP) proteins to create a variety of activator protein-1 (AP-1) complexes (1). AP-1 complexes specifically activate the expression of many other genes and so regulate cellular responses to stimuli which may result in cell proliferation, differentiation, neoplastic transformation, apoptosis, and response to stress (2). The regulated expression of c-FOS therefore plays an important role in many cellular functions. Site specific phosphorylation activates c-FOS, while sumoylation of c-FOS inhibits the AP-1 transcriptional activity (3,4). Since c-FOS expression is induced in neurons which are rapidly firing action potentials, appropriate c-Fos antibodies can be used to identify activated neurons in tissues for tracing neuronal projections and other purposes (5). Using current techniques it is possible to identify such activated cells using c-FOS staining then obtain further data on their specific protein and mRNA expression.

      This antibody has become widely used as sold by EnCor and through our numerous OEM partners, and in-formation on this can be viewed using Google scholar by searching for "RPCA-c-Fos” or by selecting here. Here is a CiteAb link to peer reviewed publications which use this antibody obtained directly from EnCor, here.



Chromogenic immunostaining of a 4% PFA fixed paraffin embedded rat hippocampus section with rabbit pAb to c-FOS, RPCA-c-FOS, dilution 1:5,000, detected in DAB (brown) following the Vector Labs immPRESS® method with citra retrieval. Hematoxylin (blue) was used as the counterstain. The RPCA-c-FOS antibody specifically labels activated neurons. This antibody performs well in testing with 4% PFA and NBF fixed mouse, human, and rat tissues. Mouse select image for larger view.

This antibody has been shown to work very on cells grown in tissue culture, being absent from serum starved cells but heavily upregulated following serum addition. See http://encorbio.com/Data/cFosabpics.html for more details. Similar finding were made with the EnCor monoclonal antibody to c-FOS, MCA-2H2.

Additional References

6. Bossis G, Malnou CE, Farras R, Andermarcher E, Hipskind R, Rodriguez M, Schmidt D, Muller S, Jariel-Encontre I, Piechaczyk M. Down-regulation of c-Fos/c-Jun AP-1 dimer activity by sumoylation. Mol. Cell Biol.25:6964-79 (2005).
7. Day HE, Kryskow EM, Nyhuis TJ, Herlihy L, Campeau S. Conditioned Fear Inhibits c-fos mRNA Expression in the Central Extended Amygdala. Brain Res. 1229:137–46 (2008).
8. Hoffman G, Smith MS, Verbalis JG. c-Fos and related immediate early gene products as markers of activity in neuroendocrine systems. Fronties in Neuroendocrinology 14:173-213 (1993).
9. Van Elzakker M, Fevurly RD, Breindel T, Spencer RL. Environmental novelty is associated with a selective increase in Fos expression in the output elements of the hippocampal formation and the perirhinal cortex. Learn. Mem. 15:899–908 (2008).
10. Dragunow M, Faull R. The use of c-fos as a metabolic marker in neuronal pathway tracing. J. of Neurosci. Mets. 29:261–5 (1989).

1. Mildle-Langosch K. The Fos family of transcription factors and their role in tumourigenesis. Eur. J. Cancer 41:2449-2461 (2005)..
2. Chiu R, et al. The c-Fos protein interacts with c-Jun/AP-1 to stimulate transcription of AP-1 responsive genes. Cell 54:541–52 (1988).
3. Karin M. The regulation of AP-1 activity by mitogen activated protein kinases. J Biol Chem. 270:16483-6 (1995).
4. Bossis G, et al. Down-regulation of c-Fos/c-Jun AP-1 dimer activity by sumoylation. Mol Cell Biol.25(16):6964-79 (2005).
5. Dragunow M, Faull R. The use of c-fos as a metabolic marker in neuronal pathway tracing. J. Neurosci. Mets. 29:261–265 (1989).


This is a new antibody but peer reviewed publications using it are beginning to come on line. So if you perform a Google Scholar search for "MCA-2H2" several publications will appear, or you can just select here.