Flow cytometry analysis to determine the number of apoptotic cells induced by apigenin treatment. TC-1 cells were co-incubated with various concentrations of apigenin (20, 40, 80 μM). Cells treated with solvent DMSO (0.1%) alone were used as controls. The cells were then stained with PE-conjugated annexin V antibody (BD, San Diego) and 7-AAD to detect the expression of annexin V and 7-AAD. Flow cytometry analysis was performed to characterize the expression of annexin V+ 7-AAD+ (apoptotic) cells among the TC-1 cells treated with apigenin. A & B. Representative flow cytometry data demonstrating the percentage of apoptotic cells at (A) 6 hours after incubation or (B) 48 hours after incubation with different concentrations of apigenin. C & D. Bar graphs depicting in the percentage of apoptotic cells at (C) 6 hours after incubation or (D) 48 hours after incubation with different concentrations of apigenin. Data shown are representative of two experiments performed (mean ± SD).