Activating protein-1 (AP-1) transcription factor has been linked to cancer and neoplastic transformation since the first cloning of jun and fos proto-oncogenes were cloned following their identification as cellular homologs of avian sarcoma virus 17 (ASV 17)-encoded oncogenes vjun and vfos 30 years ago (Curran and Franza, 1988). The gene discussed is FOS; the disease is cancer.