Specific effect of TPC1 and TPC2 receptor silencing on VWF release through H1R. ELISA assay of secreted VWF in HUVECs. Cells were treated with nontargeting siRNA (■) or with TPCs receptors siRNA (□) and then stimulated with the indicated agonists. Error bars represent SEM; n = 2 independent experiments; *P < .05 by Student t test.