Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is a member of the immunoglobulin super family and has been observed to have two paradoxical functions: tumor suppression and the promotion of tumor invasion. In the present study, we discovered that CEACAM1 functions as an adhesion inhibitor and a migration promoter. The CEACAM1 transfected cells, either 293-CEACAM1 or LOVO/trans-CEACAM1, was proved to have lower adhesion rate. Furthermore, HT29/siRNA-CEACAM1 cells had a higher adhesion rate than HT29 cells. These results indicated that CEACAM1 was an inhibitor of cell-matrix adhesion. Additionally, 293-CEACAM1 LOVO/trans-CEACAM1 cells exhibited better motility in a trans-well migration assay. N-cadherin expression levels were positively correlated with CEACAM1 in 293-CEACAM1, LOVO/trans-CEACAM1 and HT29/siRNA-CEACAM1 cells. When blocked by a GC-4 antibody, the adhesive capacities of 293-CEACAM1 and LOVO/trans-CEACAM1 were recovered and the motilities of them were suppressed, which suggested that CEACAM1 functioned through N-cadherin. (C) 2012 Elsevier Inc. All rights reserved.