GDI2 and breast cancer: Together, these data suggest that, in trastuzumab-sensitive HER2+ breast cancer, components of the RAB5/RAB7A/GDI2 subnetwork are recruited to sites of αVβ6 engagement and coordinate HER2 endocytosis, signaling, and intracellular trafficking, thus modulating HER2 bioavailability at the plasma membrane (Fig. 7A).