Thrombin and PAR1-AP induced Ca²⁺ mobilization in HUVECs and mediated release of VWF and P-selectin. Cells were plated into 96-well plates and stimulated with indicated concentrations of agonists, and Ca²⁺ was measured fluorometrically. Represented is stimulation with indicated doses of thrombin (A) and with indicated concentrations of PAR1-AP (B). The y-axes represent the relative fluorescence units. Data represent the mean ± SEM of 2 independent experiments for histamine and 3 independent experiments for PAR2-AP. (C-D) Dose-response curves were generated using the area under the curve function in SOFTmax PRO and then normalized to the fraction of maximal response and plotted with the data from Figure 2 to graphically represent the different potencies between agonists with respect to Ca²⁺ mobilization and release of VWF and P-selectin.