On the other hand, another group of cancer cell lines, such as MCF-7 breast adenocarcinoma (Fig. S3a,b), A431 vulval epidermoid carcinoma (Fig. S3c,d), CaSki squamous cell carcinoma (Fig. S3e) and MKN-74 gastric carcinoma (Fig. S3f), all of which expressed E-cadherin at high levels, formed tumor cell islands surrounded by fibroblasts in the co-cultures, suggesting stronger homophilic intercellular junctions compared with the heterophilic ones. This evidence concerns the gene CDH1 and squamous cell carcinoma.