Together with EVOO ω-9 MUFA OA, the bitter principle of olives and olive oil oleuropein aglycone is among the first examples of how selected nutrients from the so-called "Mediterranean Diet" directly regulate the expression and activity of HER2, a proto-oncogene that plays a pivotal role in malignant transformation, tumorigenesis, metastasis, and treatment failure in breast cancer disease (Figure 9). Here, ERBB2 is linked to breast cancer.