Both WWP1 and ITCH facilitate this process: WWP1 inhibits BC bone metastasis by enhancing CXCL12-mediated CXCR4 lysosomal translocation and degradation (Subik et al., 2012), while ITCH ubiquitinates CXCR4 at the plasma membrane for lysosomal degradation (Marchese et al., 2003). The gene discussed is CXCL12; the disease is breast cancer.