By introducing additional, well-defined genetic alterations that target the p53 and Ras pathways, we have induced the malignant transformation of our telomerase-immortalized human Barrett's epithelial cells, and we have developed a number of non-transformed cell lines with well-defined, growth-promoting genetic changes that might recapitulate various stages of neoplastic progression in Barrett's esophagus. The gene discussed is TP53; the disease is Barrett esophagus.