ERBB2 and breast cancer: As mentioned in the anti-apoptosis section, Dokmanovic et al. demonstrated that mutant RAC1G12V reduced the sensitivity of HER2+ breast cancer cells to trastuzumab and suggested a role of RAC1 in overcoming trastuzumab therapy in breast cancer cell populations via RAC1’s binding to the intracellular domain of the HER2 receptor, its stabilized activation, and the subsequent activation of the MAPK pathway [14].