Tumors, generated with colorectal cancer sera-treated cells, displayed epithelial features typical of colorectal adenocarcinomas, as they all stained negative for CK7, and expressed CEA, CK20, CDX-2 and AE1/AE3, which are universal markers of colorectal cancer (Fig. 1a). This evidence concerns the gene KRT7 and colorectal adenocarcinoma.