As a first example, in human breast cancer MCF7 cells and mouse embryonic stem cells (mESC), the over-expression of the protein arginine (R) methyltransferase-6 (PRMT6) that deposits the histone marks H3R2me2 and that impairs UHRF1 recruitment on the replicating chromatin, prevents the formation and activity of the DNMT1/UHRF1 complexes for maintenance methylation [141]. The gene discussed is UHRF1; the disease is breast cancer.