Effect of EGCG and TRAIL cotreatment on the expression of death receptor 5 (DR5) in SW480 and HCT116 cells. (A) SW480 and HCT116 cells were treated with TRAIL (25 ng/mL) and/or EGCG (20, 40 μM) for 24 h. Cell extracts were prepared and subjected to Western blotting with death receptor 4 (DR4) and DR5 antibodies. β-actin was used as an internal control. (B) SW480 or HCT116 cells were treated with 40 μM EGCG and 25 ng/mL TRAIL. Total RNA was isolated from the treated cells, and expression of DR5 at mRNA level was determined by RT-qPCR. The data were analyzed by two-way analysis of variance. * p < 0.05, ** p < 0.01, ***p < 0.001 vs. co-treated EGCG 40 µM and TRAIL 25 ng/mL. (C) SW480 and HCT116 cells were treated with 40 µM EGCG and/or TRAIL 25 ng/mL for 24 h. Cells were then stained with FITC-conjugated antibodies for DR5 or IgG control (negative control), and expression of DR5 on the cell surface was analyzed using flow cytometry.