Leukocyte-endothelial adhesion and angiogenesis, until recently considered as separate processes, have been shown to be linked by two recent findings: soluble cellular adhesion molecules (CAMs) involved in leukocyte-endothelial interactions are angiogenic and well known angiogenic molecules secreted by cancer or immune. cells can modulate the endothelial CAMs. This molecular link may partially explain why the overall leukocyte-endothelial interaction is often low and heterogeneous in angiogenic tumor vessels and why activated lymphocytes adhere nonuniformly to tumor vessels when injected into the tumor's blood supply.