Curcumin inhibits the proliferation of GBC-SD cells. (A) Cells were treated with varying concentrations of curcumin, and the cell proliferation and IC50 were determined by MTT assay on days 1, 2, and 3. Each value represents the mean ± SD (n = 3). (B) Curcumin suppressed colony formation of GBC-SD cells. Cells were treated with curcumin (0.75, 1.5, and 3 μmol/L) and were allowed to form colonies in fresh medium for 14 days. The photomicrographic difference (Left panel) and influence of colonies (mean ± SD, n = 3) (Right panel) in colony formation are shown.