Fig. 1.

Shikonin induces cell death in SNU-C5 and SNU-C5RR cells. (A) The chemical structure of shikonin [5,8-dihydroxy-2-(1-hydroxy-4-methylpent-3-enyl)naphthalene-1,4-dione]. (B) SNU-C5 or SNU-C5RR cells were treated with 10, 20, 30, 40, or 50 μM shikonin for 24 h. Cell viability was measured using the MTT assay. *^,**p<0.05 vs the control group in SNU-C5 and SNU-C5RR cells, respectively. (C) For the colony formation assay, SNU-C5RR cells were cultured for 11 days and treated with 38 μM shikonin on day 7. Colonies containing >400 cells were counted. *p<0.05 vs the control group.