ART4 and hepatocellular carcinoma: AFP is a 591 amino acid glycoprotein, and is expressed almost exclusively during embryonic development, with the exceptions of chronic liver inflammation [77] and 60–80% of HCC, where it is found both intracellularly (processed to peptide) and on the cell surface, presented on MHC class I. AFP is also secreted in the serum and is used as an HCC biomarker.