Fig. 1

COE treatment inhibited the viability of U251 and U87 cells by the MTT assay. Cells were incubated with the indicated concentration of COE for 24 h. Dose- and time-dependent curve of inhibition rate of COE on U251 and U87 cells by the MTT assay. Date were presented as the means ± SD of three independent experiments performed in quintuplicate. *P < 0.05, **P < 0.01, as compared with the untreated control