NCIt definition : c-FOS protein is a transcription factor critical in regulating the development of
the skeleton. c-FOS protein is a major component of the DNA-binding AP-1 transcription
complex, which also includes members of the JUN family. Each protein contains a bZIP
domain and a leucine zipper domain. FOS oncoproteins derive from mutated FOS genes.
These proteins have been found in the Finkel-Biskis-Jinkins (FBJ-MSV) and Finkel-Biskis-Reilly
(FBR-MSV) murine sarcoma viruses, which induce osteogenic sarcomas in mice. The FBJ-MSV
v-fos gene encodes a 55 kD protein and the FBR-MSV v-fos gene encodes a 75 kD fusion
protein. (from OMIM 164810 and NCI);