Furthermore, GRIN2B and GRIN2A genes have been found to be highly methylated in various carcinomas: GRIN2B in esophageal, head, and neck squamous carcinomas, gastric cancer, and lung adenocarcinomas [112,113,114]; and GRIN2A in colorectal cancer tissues [115]. This evidence concerns the gene GRIN2B and lung adenocarcinoma.