For example, in esophageal cancer, increased expression of TLR3, TLR4, TLR7, and TLR9 has been linked to esophageal squamous cell carcinomas, while TLR1, TLR2, TLR4, and TLR6 are often overexpressed in esophageal adenocarcinoma[68]. This evidence concerns the gene TLR7 and esophageal squamous cell carcinoma.