Yang M et al. [77] explored the application of CRISPR/Cas9 technology to investigate the single knockout of the CXCR4 or CXCR7 gene, as well as the simultaneous knockout of both CXCR4 and CXCR7 genes, in a triple-negative breast cancer (TNBC) cell line. The gene discussed is CXCR4; the disease is triple-negative breast carcinoma.