Figure 1.

 Effects of mithramycin (MM) on cell viability. Cell viability was examined as described in "Materials and methods" employing various concentrations of mithramycin (10 nmol/l to 1 µmol/l) applied for 48 hours to confluent systemic sclerosis fibroblast cultures in three experiments using three different cell lines, each in duplicate. The results showed that mithramycin at 1 µmol/l decreased the number of cells by over 80%, whereas 10 nmol/l (or 50 nmol/l; not shown) did not cause any significant change in cell viability. The phase contrast image shows that treatment with mithramycin at 1 µmol/l altered the shape of the cells which shrunk and lost their cytoplasm, although the nuclear staining with Hoechst did not indicate apoptotic process. No change in cell shape was seen using mithramycin at 10 nmol/l.