MT-ND6 and breast cancer: On the contrary, the transcript levels of NADH-ubiquinone oxidoreductase chain 3 (ND3), NADH-ubiquinone oxidoreductase chain 5 (ND5) and NADH-ubiquinone oxidoreductase chain 6 (ND6) were not modulated by bcl-2 overexpression in both lung and breast cancer cell lines.