Fig. 4. Immunohistochemical analysis shows that DNMT3a and -3b are localized predominantly in the nuclei.
A, rabbit polyclonal antibody against DNMT 3a was used to stain 15-μm sections of frozen liver and hepatoma. Preimmune serum from the corresponding rabbit was used as control. B, immunohistochemical analysis of hepatoma and the liver slices with DNMT3b antiserum and preimmune serum. C, liver nuclear extract (LNE) and hepatoma nuclear extracts (HNE) were used to measure maintenance and de novo DNMT activities. Incorporation of 3H-methyl group from S-adenosyl-l-methionine to hemimethylated or unmethylated DNA/μg protein was evaluated.