Traditionally, cholangiocarcinomas, lung adenocarcinomas, gastric adenocarcinomas, pancreatic adenocarcinomas, and breast carcinomas are known to be CK7 + CK20 -, while colon adenocarcinomas are CK7- CK20+, and a portion of gastric and pancreatic adenocarcinomas are CK7+ CK20+. Here, KRT7 is linked to cholangiocarcinoma.