Supported by the evidence that ALCAM is strongly expressed in all cells used in the study and that the soluble ALCAM itself significantly inhibits the cell–cell interaction, it is collectively suggest that the tumour-mesothelial interactions seen here is mediated by ALCAM, namely the ALCAM-ALCAM homotypic protein interaction resulting in the heterotypic cancer-mesothelial cell interaction. Here, ALCAM is linked to cancer.