After analysis using The Cancer Genome Atlas database identified a role for C-X-C motif chemokine ligand 12 (CXCL12), C-X-C motif chemokine receptor 4 (CXCR4) signaling pathway in oncogenic CD8+ T cells from human breast cancer, CXCR4 inhibition could enhance the efficacy of immunotherapy in the treatment of metastatic breast cancer (Chen et al., 2019). The gene discussed is CXCR4; the disease is breast cancer.