Fos B [MD397]

The Fos family of nuclear oncogenes includes c-Fos, FosB, Fos-related antigen 1 (FRA1), and Fos-related antigen 2 (FRA2). FosB responds to various cellular stimuli and shares approximately 70% sequence homology with c-Fos. However, Fos B exhibits distinct functional characteristics from c-Fos. While c-Fos can form both homo- and heterodimers with c-Jun proteins to bind DNA TPA response elements (TREs), FosB primarily operates through heterodimer formation with c-Jun and JunB proteins to activate transcription. The regulation of FosB activity involves sophisticated post-translational modifications, particularly phosphorylation, which proves essential for FosB′s stability and transcriptional activity. FosB plays vital roles in cell differentiation, proliferation, and stress responses. Deregulated expression of c-Fos, FosB, or FRA2 can result in neoplastic cellular transformation; however, FosB2 lacks the ability to transform cells.