ISG15 expression in normal hepatocyte line and HCC cell lines. A: qRT-PCR was performed to determine ISG15 mRNA expression in L02, Huh7, HLZC01 and HBV-HLCZ01, GAPDH was used as a control; B: Western blot was performed to determine ISG15 protein expression in L02, Huh7, HLZC01 and HBV-HLCZ01.