GPA33 and lung adenocarcinoma: In comparison, SATB2 and CK20 showed higher specificity, with expression in 5% and 10% of mucinous primary lung adenocarcinomas and both in 0% of TTF-1-negative non-mucinous primary lung adenocarcinomas (25–50% and 5–16%, respectively, for GPA33/CDX2/CDH17).