Cell adhesion molecules: a critical examination of their role in metastasis.

It is proposed that the arrest of circulating cancer cells in the microvasculature is mediated by mechanical interlocking of the cancer cell and vessel surfaces, as distinct from the formation of adhesive bonds utilizing cell adhesion molecules. It is also proposed that the major role of cell adhesion molecules in metastasis occurs after cancer cell arrest, when linkage to the extracellular matrix, initially the subendothelium, and consequent signal transduction results in cancer cell proliferation which is the ultimate determinant of metastasis.