Our data using a trastuzumab resistant HER2 type metastatic cancer have demonstrated the efficacy of Rac/Cdc42 inhibitors to block metastatic cancer cell functions, tumor growth, and metastasis (Montalvo-Ortiz et al., 2012; Dharmawardhane et al., 2013; Castillo-Pichardo et al., 2014); thus highlighting the utility of Rac inhibitors to overcome trastuzumab resistance. The gene discussed is CDC42; the disease is neoplasm.