Time-course studies of sulforaphane (SFN)-induced changes in cell cycle progression and histone deacetylase (HDAC) activity. Human HCT116 colon cancer cells were plated at 0.1 × 106 cells/dish and 24 h later they were treated with SFN (15 μM), or with DMSO as vehicle control (-SFN). At selected times thereafter whole cell lysates were evaluated in the (A) MTT assay, (B) ViaCount assay, (C) Guava Cell Cycle Assay, and (D) HDAC activity assay (BioMol kit), as described in Methods. Data (mean ± SE, n = 3) were from a single experiment in each case, and are representative of the findings from three separate experiments. **P < 0.01; ***P < 0.001, compared with the corresponding vehicle control.