DNMT1 and neoplasm: To determine whether the decrease in mRNA expression of these three tumor suppressor genes is regulated by DNA methylation, primary cultured leiomyoma smooth muscle cells isolated from 7 new subjects not previously used in microarrays (4 subjects were African- and 3 Caucasian-American) were treated with the DNMT inhibitor, 5-aza-dC at different concentrations (0.5, 1, 3, 5, 10, 15, 20 μM) and time points (1, 3, 5 days).