CDKN1A and gastroesophageal reflux disease: Here we showed that, compared to esophageal apparently normal tissue, gastric mucosa had significantly upregulated expression of proliferation and survival markers Ki67, BCL2, BCLxL, and CDKN1A. This observation agrees well with increased risk of adenocarcinoma in chronic gastroesophageal reflux disease (GERD), associated with the replacement of squamous epithelium with columnar [11].