CES1 and colorectal carcinoma: Ishiguro et al. reported that Caco-2 cells, albeit originated from human colorectal carcinoma, resemble rather hepatocytes with regard to expression of the isoforms CES1 and CES2 [4]: Whereas CES2 is predominantly expressed in human intestine, CES1 is the major esterase in human hepatocytes and Caco-2 cells.