Notably, a number of HER2 therapy resistance signaling pathways (Vu and Claret, 2012) are regulated by Rac signaling and targeting Rac has been shown to block breast cancer metastasis (Bracho-Valdés et al., 2011; Saci et al., 2011; Katz et al., 2012). This evidence concerns the gene ERBB2 and breast carcinoma.