Based on our and previous studies, we hypothesized that the sorafenib response rate in HCC patients with the ABCG2 rs2231142 CC genotype was lower (than that in HCC patients with the non-CC genotype) due to a functionally more effective ABCG2 efflux transporter, leading to shorter overall survival. This evidence concerns the gene ABCG2 and hepatocellular carcinoma.