In conclusion, this study shows that ISO treatment in GC cells initiated the activation of caspase-3 cascade, the upregulation of cytochrome c, Bax/Bcl-2, and cytosolic cytochrome c, and the cleavage of caspase-3 as well as PARP, resulting in mitochondrial homeostasis imbalance and apoptosis. The gene discussed is BCL2; the disease is gastric cancer.