Effects of luteolin on the viability of human myeloid leukemia cells. (a) Chemical structure of luteolin. (b) THP-1 cells were treated with vehicle (0.1% dimethyl sulfoxide (DMSO)) or luteolin (25, 50, 100 and 150 μM) for 24 h, 48 h and 72 h, respectively. Cell viability was measured by MTT assay. The data are presented as the means ± standard deviation (SD) from three independent experiments. THP-1 cells (c) and peripheral blood mononuclear cells (PBMCs) (d) were treated with vehicle or luteolin (25, 50 and 100 μM) for 24 h, and cell viability was determined by MTT assay. The data are presented as the means ± SD from three independent experiments. ## p < 0.01 represents a significant difference compared to the vehicle-treated cells (veh).