MUC1 and breast cancer: Based on our observations of mammary tumor development [21], MMT mice were arbitrarily stratified into three age groups for purpose of experiment, including: 20 to 35 days (hyperplastic lesion), 53 to 87 days (mammary intraepithelial neoplasms (MIN), a premalignant stage), and 98 to 170 days (malignant stage) and compared with control MT and MUC1.Tg mice.