text: Activator protein 1 (AP-1) is a transcription factor that regulates gene expression in response to a variety of stimuli, including cytokines, growth factors, stress, and bacterial and viral infections. AP-1 controls a number of cellular processes including differentiation, proliferation, and apoptosis. The structure of AP-1 is a heterodimer composed of proteins belonging to the c-Fos, c-Jun, ATF and JDP families.
  History
  AP-1 was first discovered as a TPA-activated transcription factor that bound to a cis-regulatory element of the human metallothionein IIa (hMTIIa) promoter and SV40. The AP-1 binding site was identified as the 12-O-Tetradecanoylphorbol-13-acetate (TPA) response element (TRE) with the consensus sequence 5’-TGA G/C TCA-3’. The AP-1 subunit Jun was identified as a novel oncoprotein of avian sarcoma virus, and Fos-associated p39 protein was identified as the transcript of the cellular Jun gene. Fos was first isolated as the cellular homologue of two viral v-fos oncogenes, both of which induce osteosarcoma in mice and rats. Since its discovery, AP-1 has been found to be associated with numerous regulatory and physiological processes, and new relationships are still investigated.