CPE and hepatocellular carcinoma: sEVs from highly metastatic cell lines were found to be enriched in carboxypeptidase E (CPE) and S100A4 and promote the proliferation and metastatic potential of non-CSC HCC cells, through activating c-myc/cyclin D1 and STAT3/OPN signaling, respectively, in the recipient cells (10, 11).