 Human osteosarcomas analyzed for c-fos expression have given positive results in more than half the cases and c-fos expression has been associated with higher frequency of relapse and poor response to chemotherapy.Several studies have raised the idea that c-Fos may also have tumor-suppressor activity, that it might be able to promote as well as suppress tumorigenesis.Supporting this is the observation that in ovarian carcinomas, loss of c-Fos expression correlates with disease progression.