Isolated from Elephantopus scaber L.,a Chinese medicinal herb that is widely used to prevent and treat cancers in China,isodeoxyelephantopin (ESI) exerted anti-tumor effects on several cancer cells.However,its anti-tumor mechanism is still not clear.In this study,we found that ESI could induce G2/M arrest and subsequently stimulate cell apoptosis in dose- and time-dependentmanners.We used SILAC quantitative proteomics to identify ESI-regulated proteins in cancer cells,and found that 124 proteins weresignificantly altered in expression.