Fig. 3. Determination of relative amount of surface-exposed VE-cadherin in response to cytochalasin D (10 µM) and A23187 (10 µM) assayed by trypsin treatment of MyEnd monolayers in presence and absence of Ca²⁺ and subsequent visualisation of VE-cadherin by western blotting. Virtually all VE-cadherin molecules are exposed on the cell surface and are sensitive to extracellular proteolysis. The total amount of VE-cadherin remains constant as judged from constant immunoblotting signal in the presence of Ca²⁺ that renders cadherins resistant to trypsin cleavage.