Influence of survivin overexpression on proliferation and apoptosis of chondrosarcoma cells in vitro. A: Overexpression of human full length survivin by transfection of plasmid DNA led to a significant increase of protein level, as measured by immunoblot. Empty vector pcDNA3 was transfected as control. B: MTT - analysis over 5 days after transfection showed no influences on the proliferative activity of SW1353. C and D: Overexpression of survivin resulted in no alterations of spontaneous apoptotic rate as measured by caspase 3/7 activity (C) and by analysing the sub-G0/1-phase fraction by using the fluorescence-activated cell sorting-propidium iodide staining method (D). When SW1353 cells were exposed for 24 hours to doxorubicin (5 μM) (right) the apoptotic fraction and caspase activity of not transfected and pcDNA3 transfected cells increased markedly. Transfection of survivin resulted in significantly reduced rates of apoptosis after cytotoxic treatment. The error bars represent +/-SEM. P values less than 0.05 were considered significant (*). The original results of one representative experiment are shown.