Iron increases the expression of mdm2 by murine synovial cells. Normal murine synovial cells were cultured in the presence of iron citrate (10 μM) for 7 days after which RNA was isolated, subjected to RT-PCR, and then analyzed by gel electrophoresis with ethidium bromide and photographed under UV transillumination. Lane 1, markers; lane 2, control synovial cells maintained in standard culture medium without added salt; lane 3, synovial cells exposed to sodium citrate; lane 4, cells cultured in the presence of 10 μM ferric citrate for 7 days. Arrow indicates mdm2. Data shown are representative of 6 total experiments performed.