Proliferation of Ewing tumor cells treated with tyrosine kinase inhibitors for 72 hours. Cells were treated with indicated concentrations of drugs and relative cell proliferation was assayed in comparison to untreated control cells. Results shown are the means of ten replicates and error bars show 95.0% confidence interval of mean. Asterisks indicate significant inhibition of proliferation at p values indicated in the figures. Data represents one of three experiments yielding similar results.