PTGS2 and Hermansky-Pudlak syndrome: In two different models of HPS, parecoxib was used to inhibit the activation of the COX-2/PGE2 signaling pathway, thereby, reducing the accumulation of activated CD68+-macrophages [203] as well as the directional migration of pulmonary EC [204], which are two major pathophysiological processes in the development of HPS.