To confirm this observation, we conducted RT-qPCR analysis using 40 tumor samples from HCC patients to detect GSTZ1 and NQO1 mRNA expression, and we observed a negative correlation between GSTZ1 and NQO1 expression (r = − 0.37, p = 0.0197, Fig. 4d). The gene discussed is GSTZ1; the disease is hepatocellular carcinoma.