To examine whether over-expression or knockdown of USP15 affects the HBx protein levels in a HCC cell line with “endogenous” HBx we ectopically expressed a carboxyl-terminal truncated form of HBx (Ct-HBx, depletion of amino acids 130–154) in Huh7 cells (the stable cell line is designated here as Huh7/Ct-HBx). This evidence concerns the gene USP15 and hepatocellular carcinoma.