The expression of miR-29s is inversely correlated to DNMT3A and DNMT3B in lung cancer tissues, and miR-29s directly target the 3'-UTRs of both DNMT3A and DNMT3B. The enforced expression of miR-29s in lung cancer cell lines restores normal patterns of DNA methylation. The gene discussed is DNMT3B; the disease is lung carcinoma.