The effects of apigenin on the viability in four cell lines, WI-38, T-24, HT-1376 and PC-3 cells. (A) Chemical structure of apigenin. (B) Three cultured cells (T-24, HT-1376, PC-3) and (C) WI-38 cells were treated with or without apigenin under various concentrations (0, 1, 5, 10, 20, 30, 40, and 50 μg/ml) for 24 h. Thereafter, cell viabilities were determined by MTT assay. The survival cell number was directly proportional to formazan, which was measured spectrophotometrically at 563 nm. Values represent mean ± SD of three independent experiments (*P < 0.05, **P < 0.01, ***P < 0.001 compared with the untreated control (dose 0).