Members of the Bcl-2 family proteins with either proapoptotic (e.g., Bax, and Bak) or antiapoptotic (e.g., Bcl-2, and Bcl-xL) functions regulate the mitochondrial membrane permeability (MMP) in apoptosis, and decreases in antiapoptotic and increases in proapoptotic Bcl-2 family proteins were observed during apoptosis of cancer cells under chemical stimulation. The gene discussed is BCL2; the disease is cancer.