To deduce the signaling pathways by which TNF-α sensitized MDA-MB-231 breast cancer cells to WA and Cel resulting in apoptosis, cells were treated with WA (1, 2.5, 5 μM) or Cel (0.5, 1, 2 μM) with or without TNF-α and expression levels of caspase-3 and -9, as well as caspase-3 activity, were determined (Fig. 3A, B). Here, TNF is linked to breast cancer.