In epigenetic drug discovery, including DNMT1, efforts are increasing to design and analyze focused libraries of DNMT inhibitors. Our research group recently reported a comprehensive analysis of the chemical content, diversity, and chemical space coverage of eleven commercial epigenetic-focused libraries with over 50,000 molecules. In that study, the most and least diverse chemical libraries were identified . Moreover, separate research endeavors have identified five compounds, including glyburide and panobinostat (Figure ), as DNMT1 inhibitors . Also highlighted is the quinazoline UNC-0646 (Figure ), initially identified as a G9a inhibitor, which has been recently discovered to also effectively inhibit DNMT1 at the nanomolar level .