NQO1 and hepatocellular carcinoma: On the other hand, similar to the analysis in HCC patient samples, we observed that the liver cancer cell lines HepG2, Huh7 and Li7 showed high NQO1 levels; PLC/PRF/5 cells exhibited moderate NQO1 expression; and Hep3B, SNU-182, and SK-HEP1 cells expressed low or undetectable NQO1 (Figure 2E).