ERBB2 and breast cancer: We therefore analyzed the level of RAC1-GTP in a panel of human breast cancer samples from patients who had been followed for several years, including luminal B-like tumors (positive for either estrogen or progesterone receptor expression, HER2-negative status, and mitotic grade >1) and triple-negative (TNBC) tumors (lack of HER2 (Human Epidermal growth factor Receptor 2), estrogen, and progesterone receptors) (Table S1).