KRT19 and metastatic colorectal cancer: Xiao et al. reported that cytokeratin 19 (CK19) was enriched in the exosomes that were derived from colorectal cancer cells, that carbohydrate antigen 125 (CA125) was elevated in the exosomes from metastatic colorectal cancer cells, and that tumor-associated glycoprotein 72 (TAG72) was detected in the exosomes from 5-fluorouracil (5-FU)-resistant colorectal cancer cells [240].