Thioridazine (THD), an antagonist of the dopamine receptor D2, is a potent anti-anxiety and anti-psychotic that in combination with radiotherapy promotes G0/G1 phase cell cycle arrest by CDK4 and cyclinD1 downregulation on the esophageal squamous cell carcinoma (ESCC) ECA-109 and TE-1 cell lines. This evidence concerns the gene CDK4 and esophageal squamous cell carcinoma.