Accordingly, several studies had previously reported about aberrant methylation of ALDH1L1 promoter in lung adenocarcinoma, hepatocellular carcinoma (Oleinik et al., 2011), and esophageal squamous cell carcinoma (Chen et al., 2015), supporting the idea that hypermethylation of ALDH1L1 is a major mechanism for suppression of the gene in cancer. Here, ALDH1L1 is linked to lung adenocarcinoma.