DIM inhibits CDK2 activity and reduces the levels of phospho-Rb and E2F-1 in HT-29 cells. Cells were treated with different concentrations of DIM as described in Figure 1. (A) CDK2 was immunoprecipitated and analyzed via an in vitro kinase assay using histone H1 as a substrate. An autoradiograph of the dried gel, which is representative of three independent experiments, is shown. (B) Cell lysates were analyzed via Western blotting. Photographs of the chemiluminescent detection of the blots, which were representative of three independent experiments, are shown. The relative abundance of each band to its own CDK2 (A) or β-actin (B) was quantified, and the control levels were set at 100%. The adjusted mean ± SEM (n = 3) of each band is shown above each blot. *Significantly different from 0 μmol/L DIM, P < 0.05.