Percentage of cells undergoing apoptosis or necrosis.

Early and late apoptosis measured by annexin V and propidium iodide staining in human breast cancer cells revealed that the metastatic MDA-MB-231 cells pretreated for 24 h with artesunate, became resistant to further treatment. While MDA-MB-468 cells showed significantly increased early (6.18%) and late apoptosis (14.63%), MDA-MB-231 cells showed only a minimal increase in early apoptosis (2.29%) and no increase in late apoptosis 24 h after additional artesunate treatment.