CASP3 and cancer: Furthermore, scavenging of reactive oxygen species (ROS) by antioxidant NAC or Tiron inhibited the release of cytochrome c, caspase-3 activity, and eventually rescued cancer cells from Ru1-mediated apoptosis, suggesting that Ru1 inducing apoptosis was partially caspase 3-dependent by triggering ROS-mediated mitochondrial dysfunction in A549 and NCI-H460 cells.