Emodin-induced anti-proliferation of HeLa cells. HeLa cells were treated with emodin at doses of 0, 10, 20, 30, 40, and 50 μM for 24, 48, and 72 h. Cell viability was evaluated with the MTT assay and results are reported as relative cell viability (%). All data were normalized to the control group which was considered to be 100%. The result showed that emodin inhibited proliferation of HeLa cells in a dose- and time-dependent manner. *P<0.05 versus control group (0 μM) (two-way ANOVA followed by the Tukey post hoc test).