In the November 15th issue of G&D, Dr. Sriharsa Pradhan (New England Biolabs) and colleagues demonstrate that the DNA methyltransferase, DNMT1, and the histone methyltransferase, G9a, interact to coordinate DNA and histone methylation during DNA replication. The researchers found that the two proteins co-localize and positively influence each other's catalytic activities. Furthermore, siRNA-mediated knockdown of DNMT1 not only impairs DNA methylation as expected, but also impairs histone H3K9 methylation. This work suggests that DNMT1 and G9a may cooperate to maintain epigenetic marks during cell division, and, as Dr. Pradhan points out, now that this interaction has been uncovered "we go to work on uncovering the coupling mechanism."