Fig. 1.

Cytotoxic effect of shikonin in human colon cancer SNU-407 cells. Cells were treated with (A) the indicated concentrations of shikonin for 48 h. Viability was assessed by the MTT assay. ^*p<0.05 vs. control cells. (B) Long-term cytotoxic effects of shikonin were detected by a colony formation assay. Approximately 500 colonies were seeded into each 60-mm dish, treated with shikonin, and incubated for 14 days. The resultant colonies were stained using a Diff-Quik kit. ^*p<0.05 vs. control cells.