Effect of nobiletin on viability of PC-3 and DU-145 cells. (a) DU-145 cells, (b) PC-3 cells. Cells (5.0 × 103 /well) were seeded in 96-well plates, incubated for 16 h, and treated with nobiletin for 24 h. Cell viability was colorimetrically determined by a MTS-based method and expressed as percentages of control. Data represents mean ± SE from 3 independent experiments. *P < 0.05 as compared to control. **P < 0.01 as compared to control.