RECK and lip and oral cavity carcinoma: RECK down-regulation or promoter hypermethylation have been confirmed in many human cancers, including pancreatic cancer, breast cancer, lung cancer, colorectal cancer, cholangiocarcinoma, gastric cancer, prostate cancer, oral cancer, esophageal cancer, and osteosarcoma, and correlated with tumor metastasis or poor prognosis [11]–[23].