CXC chemokine 12 has a strong chemotactic effect on colon cancer cells and acts on CXC chemokine receptor 4 on the surface of tumor cells to activate the NF-κB p65 pathway, which promotes the further release of exosomes rich in miR-203a-3p from colon cancer cells, thus forming a positive feedback loop.[83] Song and colleagues reported that the content of miR-21-5p in exosomes of ESCC origin was associated with the progression of ESCC. This evidence concerns the gene NFKB1 and neoplasm.