Methylation, the addition of methyl groups to DNA, is key in the control of bone marrow cells and can contribute to, or cause, certain types of acute leukemia. New cancer drugs are targeting the enzymes that influence this phenomenon. In the New York Times on December 4, 2014 Gretchen Reynolds reports on a study reported in Epigenetics in which investigators did an intriguing experiment: they had volunteers exercise one leg only and then biopsied muscles in the exercised and non-exercised leg. The exercised limb showed extensive methylation in the DNA of muscle cells, implying that genes in the exercises leg were turned on in some manner. Just what those genes are doing is still being investigated but the logical conclusion is that they are turned on to grow the muscle or make its contractions more forceful. This study is is part of a much larger effort to understand how changes in DNA other than mutations can effect bodily function. Dr. Stark comments, “Epigenetics will play a large role in understanding the ways in which we can manipulate the metabolism of the cancer cell. This required a paradigm shift for basic cancer researchers, thinking about ways other than classic DNA base substitutions that cancers could arise from normal cells.”