Furthermore, female mice lacking Sirt3 appear to spontaneously develop estrogen receptor-positive (ER+), high Ki-67, poorly differentiated, mammary gland tumors that seem to be similar, as analyzed by immunohistochemistry, to human luminal B breast malignancies, which account for the most death cases among all breast cancer patients in the United States 20. This evidence concerns the gene ESR1 and breast carcinoma.