PLD1 knockdown inhibits VWF secretion. (A) HUVECs were transfected with a plasmid that encodes shRNA that targets human PLD1 or firefly luciferase (shLUC). Cell lysate were prepared 72 hours after transfection and probed for PLD1. Membrane was stripped and reprobed for β-actin. (B-C) Seventy-two hours after transfection, HUVECs were incubated with medium that contained Stx1B (B) or Stx2B (C). VWF secretion and deposition on HUVEC surface was measured as described in “Methods.” Results from 3 independent experiments were averaged and plotted. Values were significantly different from the control (Mock) condition (P < .01).