RARA and esophageal squamous cell carcinoma: Since it has been suggested by the results of others (19) that basal levels of retinoic acid receptor mRNA expression in normal unaffected tissue might differ between patients with SCC and controls, protein levels of RARα, β, γ, and RXRβ were determined in esophageal tissue obtained form controls and compared with protein levels measured in normal esophageal tissue obtained from patients with esophageal SCC.