GRK3 and breast cancer: The data show that relative GRK3 expression correlates with tumorgenicity, invasiveness, and metastatic potential in both human (Figs 1, 2 and 3) and mouse models (Fig 5 and Table 1) and further, that manipulating GRK3 levels directly affects the chemotactic and metastatic potential of breast cancer cells (Figs 3 and 7).