F8 and hepatocellular carcinoma: We previously have shown that the increased expression of ET3 is conferred through enhanced posttranslational processing of the nascent fVIII peptide.13 To determine if improved biosynthetic efficiency was retained by the AAV-HCR-ET3 expression cassette, an in vitro transfection experiment utilizing the human hepatocellular carcinoma HepG2 cell line was performed.