We determined the mRNA levels of c-jun and c-fos in the liver of C3H-H-2 degrees jvs mice. Both were higher in jvs mice than in normal mice. The level of c-jun mRNA increased gradually after birth, but in the control mice there was almost no change. In addition, alpha-fetoprotein and aldolase A mRNA levels were also higher than in normal littermates. These results suggest that the pattern of the gene expression in jvs mice partly resembles the one that occurs in undifferentiated hepatocytes and/or hepatocellular carcinoma.