RARS1 and esophageal cancer: In the past decades, there were lots of studies reporting that alterations of RARs expressions were associated with the development of some diseases, such as squamous-cell carcinoma [4], mammary carcinomas [5], esophageal cancer [6], etc. However, the role of RARs is complicated, and the mechanisms of RARs in the progression of diseases are not elucidated.