FIG. 6.
Dnmt3a and Dnmt3b mutually stimulate de novo methylation at the Oct4 promoter in differentiating ES cells. (A) Expression of ectopic (with gray-shadowed background) and endogenous methyltransferases in stably established ES cell lines by Western blotting. Catalytically inactive mutant Dnmt3b1 V732G, Dnmt3a1 E752A, or wild-type (WT) counterparts were stably introduced into Dnmt3a−/−, Dnmt3b−/−, or Dnmt3a−/−3b−/− ES cells. (B) Analysis of Oct4 methylation 3 days upon RA induction by COBRA. Each bar represents an individual stable cell line.