Fig. 2

The anti-survival effect of TRAIL alone and the combination of azithromycin and TRAIL in colon cancer cells. a The purification of TRAIL protein. M represents marker; 1 represents TRAIL protein; 2 represents Western blot by His-tag antibody; 3 represents Western blot by anti-TRAIL antibody. b The proliferation of four types of colon cancer cells (SW620, DiFi, SW480 and HCT-116) treated with various concentrations of TRAIL for 24 h, as detected by a SRB assay. c The synergistic inhibitory effect of azithromycin and TRAIL on the proliferation of SW480 and HCT-116 cells. HCT-116 cells were treated with azithromycin (25–150 µmol/L) and TRAIL (7.8125 and 15.625 nmol/L) for 48 h; SW480 cells were treated with TRAIL at 50 and 100 nmol/L. The survival rate was calculated as a ratio to the control group (untreated cells). CDI value < 1 represents a synergistic effect and CDI < 0.7 indicates a robust synergistic effect. Values represent the mean ± SD of three independent samples. Each experiment was repeated three times. AZM represents azithromycin