Pharmacological inhibition of Topoisomerase I in ovarian cancer cell lines. A. TPT toxicities were measured by XTT assay. Cells were seeded at 1000 cells/well in 50 μl and 3 replicates 16–20 hours prior to the addition of the drug. XTT assay was performed 3 days later upon drug treatment. The viability was calculated relative to no drug treatment and the error bars represent standard deviations calculated from 3 replicates. Shown is a representative of 2 – 5 independent experiments depending on cell lines. IC50 values were calculated by CompuSyn after converting relative viability values to fraction affected numbers. B. The expression level of Topoisomerase I was examined using total lysates by Western blotting. GAPDH was used as a loading control.