Prerequisites for tumor cell transendothelial migration. Single tumor cells adhere to the endothelium via cell adhesion receptors like integrins, muccins, or immunoglobulins and their counter-receptors on endothelial cells. Many other factors like enzymes, cytokines/chemokines influence these interaction as well as biomechanical properties of both cells (CSK-dynamics, CSK-fluidity, cell stiffness, and contractile force generation).