The antiproliferative effect of extracts of X. aethiopica on various cancer cell lines. (A) The indicated cell lines were treated with either 70% ethanol (control vehicle) or 25 μg/ml X. aethiopica extract for 4 days. Cell numbers were counted and normalized to the control value. Student's t-test gives a p-value < 0.005 for all cell lines. (B) Dose-response curves for the effect of X. aethiopica extracts on the viability of HCT116, KG1a, U937 cells and normal fibroblasts. Cells were treated with various concentrations of X. aethiopica extract for 4 days and cell viability was determined using a WST-1 assay (triplicate determination). The values are the means of three independent experiments and the error bars represent the standard deviation.