NAPSA and colon adenocarcinoma: To further elucidate the frequency of aberrant TTF-1 and Napsin A expression in gastrointestinal cancers, we performed immunohistochemical staining of large collections of esophageal, gastric and colonic adenocarcinomas using anti-TTF-1 antibodies (SPT24 clone) and anti-Napsin A antibodies (IP64 clone) applied on tissue microarrays (TMAs).