It has been shown extensively by others that treatment of leukaemia cell lines employed in our work (Daudi, Jurkat, Kasumi-1, Mutz-1 and K562) with the HDAC inhibitor TSA or the DNA methyltransferase 1 inhibitor 5-azadC has a profound impact on the expression of several genes and decreases proliferation and clonogenic survival and increases the level of apoptotic markers (Blagosklonny et al, 2002; Zhu and Otterson, 2003; Karagiannis et al, 2004; Liu et al, 2004; Yokota et al, 2004; Furukawa et al, 2005). The gene discussed is DNMT1; the disease is leukemia.