Another highly down-regulated gene, CDO1 (FC −60.54), encodes cysteine dioxygenase type 1 and is a tumor suppressor found silenced by promoter methylation in different cancer types, such as non-small cell lung cancer and gastrointestinal cancers, including liver cancer [49,50,51,52]. The gene discussed is CDO1; the disease is non-small cell lung carcinoma.