Together, the data presented here demonstrate that: (i) an increase in mtDNA copy number is necessary for KRAS-driven tumor formation in the lung (Fig. 6A); (ii) higher mtDNA content confers an advantage to tumor cells and results in increased tumor burden (Fig. 6A); and (iii) failure to increase mtDNA copy number in tumor cells impairs tumor growth (Fig. 6B). This evidence concerns the gene KRAS and neoplasm.