Consistent with these data obtained in human BC cell lines, mammary tumors from MMTV-PyMT+/−; Sirt6+/− mice exhibited decreased complex I, III, and IV activity as well as reduced ATP/AMP ratio as compared to tumors from MMTV-PyMT+/−; Sirt6+/+ mice (Fig. 5a–d). Here, SIRT6 is linked to breast cancer.