(A) Effects of cisplatin and/or UV-C on cell proliferation in human colorectal cancer cells. SW480 and DLD-1 cells were either exposed to 10 J/m² UV-C (lanes 3), treated with 10 μM cisplatin (lanes 2), or received both (lanes 4). Twenty four h later, the measurement of BrdU incorporation was performed using cell proliferation ELISA (BrdU). Results are expressed as percentage of incorporation with 100% representing that by untreated control cells (lanes 1). (B) SW480 cells were treated with 10 μM cisplatin (group 2), 10 J/m² UV-C (group 3) or combination of 10 μM cisplatin and 10 J/m² UV-C (group 4). The cells were then stained with propidium iodide (PI) to analyze progression of cell cycle. The distribution of cells in the apoptosis and each phase of cell cycle were calculated in each group. Bars designate SD of triplicate assay. The asterisks (*) indicate significant decrease (p < 0.05) as compared to the corresponding control, respectively.