RAC1 and breast cancer: 28 Furthermore, a recent study demonstrated that Arf6 potentiated the formation of Rac1 and Wave dependent ventral F actin rosettes in breast cancer cells upon epidermal growth factor (EGF) stimulation.29 In addition, the authors could demonstrate that interference with ARF6 expression resulted in poor activation and plasma membrane localization of Rac1 in response to EGF treatment.