Mechanisms of tumour cell metastasis.

Abercrombie and his colleagues have accumulated evidence that changes in the heterotypic contact-inhibition response are largely responsible for the invasiveness of cells, at least in culture. We have identified a 37,000 Mr protein on the surface of mouse fibrosarcoma cells that is involved in their in vitro invasion. Blocking this protein with specific antibodies inhibits the invasion of chicken heart fibroblasts by the tumour cells and normal heterotypic contact inhibition is restored. These results are presented in the general framework of metastatic mechanisms and we review a selection of more recent studies aimed at describing the metastatic phenotype in molecular terms.