Elucidate the mechanisms involved in the development of tumor metastases, for rational methods of preventing and/or containing tumor metastases can only be developed after the pathogenesis of metastases is known. Elucidation of the cancer cell-endothelium interaction and the effect cancer cells have on the endothelium. To obtain greater information on the cancer cell-endothelium interaction, the following will be undertaken: morphologic examination by time lapse cinemicroscopy and scanning electron microscopy of cancer cell-endothelium interaction in vitro; qualification of the number and strength of cancer cell-endothelial interaction and features that influence the interaction; and determination of the effect cancer cells have on endothelium.