Hypomethylation of NOX4 has been observed in various cancer types, including breast cancer, lung squamous cell carcinoma, bladder cancer, lung adenocarcinoma, prostate cancer, endometrial cancer, gastric cancer, thyroid cancer, and gallbladder cancer, suggesting that epigenetic modifications may contribute to its dysregulation in cancer. This evidence concerns the gene NOX4 and lung adenocarcinoma.