CXCR4 and lung adenocarcinoma: For example, the presence of circRNA in exosomes (exo-hsa_circRNA) was found to be associated with CXCR4 expression which was confirmed to be related to the lymph node metastasis of lung adenocarcinoma in vivo, so it may be a predictor of lymph node metastasis in lung adenocarcinoma [111].