PTTG1 and breast cancer: Among the pathologically defined lobular tumors, 58% were luminal A or luminal B, while in the model defined lobular tumors, 72% were luminal A or B (53% and 19%, respectively), though the PAM50 intrinsic breast cancer subtype classification model contains only one gene in common with the lobular ductal model proposed here (pituitary tumor-transforming 1, PTTG1).