MMP9 and esophageal cancer: The study by Xia et al revealed that a protein complex composed of LCN2, LOXL2, and MMP9 promoted tumor metastasis in esophageal cancer.[29] The study by Li et al[30] found that CEBPB was an immune checkpoint gene in triple-negative breast cancer, and it could control myeloid-derived suppressor cells and tumor immunity through its specific subtypes.