MT-ND6 and lung adenocarcinoma: Combined with the results that mitND6 gene nonsense and missense mutation could inhibit of NADH dehydrogenase activity and increase the level of ROS in A549 cells, we suggest that mitochondrial ND6 gene nonsense and missense mutations may induce ROS over-production by reducing the activity of NADH dehydrogenase and further regulate cell migration and invasion in lung adenocarcinoma cells.