<prompt> Platelate aggregation is caused by all, except ?Thromboxane A2SerotoninProstacyclin PGI2Thrombin  <response>: Ans. is c i.e., Prostacyclin PGI2Factors promoting platelet aggregation : ADP, TXA2 , epinephrine, serotonin, vWF, fibrinogen, collagen, immune complex, thrombin, thrombospondin.Factors inhibiting platelet aggregation : PGI2, NO, endothelin, bradykinin. 