In support of the malignant nature of tumors from CCl4-treated mice, we investigated the expression of genes, such as alpha-fetoprotein (Afp), trefoil factor 3 (Tff3), stearoyl-coenzyme A desaturase 2 (Scd2), lipoprotein lipase (Lpl), and glypican 3 (Gpc3), which are known markers of hepatic tumor progression.30, 31 As positive controls for mouse HCC, we used samples from control DEN-induced HCC obtained in TG221 mice in previous studies.16, 20 The level of expression was progressively increased from normal liver, cirrhotic tissue, CCl4-induced tumors, and DEN-induced HCC (Figure 4A). The gene discussed is AFP; the disease is hepatocellular carcinoma.