Downstream signalling in A549 lung cancer cells treated with coumestrol and inhibition effects of coumestrol on cellular viability in three cancer cell lines. A. Phosphorylated Akt (Ser129), total Akt, and PARP were measured by western blot analysis. B-actin was used as loading control. Expression of pAKT s129 was quantified using ImageJ software and the mean of relative expression level to β-actin or to total AKT was presented (mean ± SD). B. Coumestrol significantly decreased the expression of pAKT s129 in A549 cells (*, p < 0.05, Student t-test). C. Annexin V analysis of apoptosis induced by CK2α siRNA. A549 cancer cells were treated with 100 nM CK2α siRNA and 100 nM control siRNA for 72 h. D, E, F. A549, Jurkat and Hela cells were cultured in the absence and in increasing concentrations of coumestrol (0.1 uM to 100 μM) as indicated. Cellular viability (normalized to DMSO control) was measured after 48 hours using CellTiter-Glo®Luminescent Cell Viability Assay. Data points represent the average of IC50 value of coumestrol in triplet experiments and bars indicate SD.