ERBB2 and breast cancer: For example, breast cancer patients that express progesterone receptor (PR) and estrogen receptor (ER) (luminal A breast cancers are ER+PR+HER2- or ER+PR+HER2+, while luminal B are ER+PR+HER2-) are treated with endocrine therapies and/or with the antibody Herceptin, in combination with chemotherapy and/or radiotherapy [3].