Mouse Monoclonal Antibody to c-FOS (cFos, Fos, AP-1) Cat# MCA-1B62

      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.

Chromogenic immunostaining of a 4% PFA fixed paraffin embedded rat hippocampus section with mouse mAb to c-FOS, MCA-1B62, dilution 1:2,000, detected with DAB (brown) using the Vector Labs ImmPRESS method and reagents with citrate buffer retrieval. The antibody strongly recognizes the nuclei of a few spontaneously activated neurons against a background of apparently unreactive cells. This antibody performs well in testing with both 4% PFA and standard NBF fixed rat, mouse and human tissues. Mouse select image for larger view.



Immunofluorescent confocal analysis of HeLa cells stained with mouse mAb to c-FOS, MCA-1B62, dilution 1:2,000 in red, and chicken pAb to vimentin, CPCA-Vim, dilution 1:1,000, in green. The blue is DAPI staining of nuclear DNA. HeLa cells were incubated in PBS without fetal bovine serum (FBS) for 24 hours. Then the cells were either stimulated with 20% FBS for 2 hours or treated with PBS for 2 hours as a control. As shown in the top two and the lower left quadrants of the image the c-FOS antibody strongly labels the nuclei of cells in response to FBS stimulation. In stark contrast, as shown in the lower right quadrant, the unstimulated control cells show virtually no c-FOS staining. The stimulated and control cultures were processed for antibody staining simultaneously and confocal images were made of both cultures with the exact same laser, brightness and contrast settings.



Chromogenic immunostaining of a 4% PFA fixed paraffin embedded mouse olfactory bulb section with mouse mAb to c-FOS, MCA-1B62, dilution 1:2,000, detected with DAB (brown) using the Vector Labs ImmPRESS method and reagents with citrate buffer retrieval. The antibody strongly recognizes the nuclei of a few spontaneously activated olfactory neurons against a background of apparently inactive cells. Mouse select image for larger view.



Chromogenic immunostaining of a 4% PFA fixed paraffin embedded mouse hippocampus section with mouse mAb to c-FOS, MCA-1B62, dilution 1:2,000, detected with DAB (brown) using the Vector Labs ImmPRESS method and reagents with citrate buffer retrieval. The antibody strongly recognizes the nuclei of a few spontaneously activated neurons against a background of apparently inactive cells. Since mouse tissues contain endogenous mouse IgGs notably in blood vessels, using a mouse antibody on mouse tissue may result in significant irrelevant signal and so is not optimal. We would recommend our rabbit polyclonal to c-FOS, RPCA-c-FOS, for this purpose. Mouse select image for larger view.



Immunofluorescent analysis of mouse Hippocampus stained with mouse mAb to c-FOS, MCA-1B62, dilution 1:1,000 in red, and costained with rabbit pAb to GFAP, RPCA-GFAP, dilution 1:5,000 in green. Blue is Hoechst staining of nuclear DNA. Following transcardial perfusion of mouse with 4% paraformaldehyde, brain was post fixed for 24 hours, cut to 40μM, and free-floating sections were stained with the above two antibodies. The c-FOS antibody stains nuclei of two spontaneously active hippocampal neurons against a background of numerous apparently not activated cells. Inset shows a c-FOS expressing cell from the same specimen which appears to be an astrocyte based on GFAP staining. Since mouse tissues contain mouse IgGs notably in blood vessels, using a mouse antibody on mouse tissue may result in significant irrelevant signal and so is not optimal. We would recommend our rabbit polyclonal to c-FOS, RPCA-c-FOS, for this purpose. Mouse select image for larger view.

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).