Effect of β-sitosterol (ST) on growth and cell death in human cancer cells. (A) Chemical structure of β-sitosterol, Chemical formula:17-(5-Ethyl-6- methylheptan-2-yl)-10,13-dimethyl-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H cyclopenta[a]phenanthren-3-ol. Cells were plated overnight and treated with either DMSO control or 30, 60 and 90 μM β-sitosterol for 48 and 72 h. At the end of treatment, cells were collected and counted with hemocytometer after staining with trypan blue dye using phase contrast inverted microscope for total cell number of (B) A431, (C) A549 and (D) MDA-MB-231; and percent dead cells of (E) A431, (F) A549 and (G) MDA-MB-231. Data shown are mean ± S.E. of triplicate samples for each treatment. #, p < 0.05; $, p < 0.01; *, p < 0.001 compared with the respective controls.