Specimens were collected from esophageal adenocarcinoma patients undergoing esophagectomy for adenocarcinoma at the University of Michigan Health System between 1991 and 2012. Written consent was obtained from each patient according to the approval and guidelines of the University of Michigan institutional review board. Patients receiving treatment with chemotherapy and/or radiotherapy prior to surgery were excluded. Tissue samples were fresh-frozen in liquid nitrogen and stored at -80 °C until use. Overall design: Cellularity of tumor samples were assured to be greater than 70% before sample RNA was isolated. RNA was extracted from histological confirmed adenocarcinomas arising at the gastroesophageal junction (GEJAC: n=70) or within the tubular esophagus (tEAC: n=52), along with histologically normal esophageal squamous (NE: n=8) and gastric mucosa (NG: n=5) sections collected at the time of tumor resection and processed for hybridization on Affymetrix Human Gene 2.1 ST Array.