C-Fos

Overview
In molecular biology, c-Fos is a cellular proto-oncogene belonging to the immediate early gene family of transcription factors. c-Fos has a leucine-zipper DNA binding domain, and a transactivation domain at the C-terminus. Transcription of c-Fos is upregulated in response to many extracellular signals, e.g. growth factors. Additionally, phosphorylation by MAPK, PKA, PKC or cdc2 alters the activity and stability of c-Fos. Members of the Fos family dimerise with Jun to form the AP-1 transcription factor, which upregulates transcription of a diverse range of genes involved in everything from proliferation and differentiation to defense against invasion and cell damage.

The AP-1 complex has been implemented in transformation and progression of cancer, and both Fos and Jun were first discovered in rat fibroblasts.

The viral homologue of c-Fos, v-Fos, is found in the retrovirus Finkel–Biskis–Jinkins murine osteogenic sarcoma virus.