IL6R and pulmonary arterial hypertension: Multiple dysfunctions in the endocytic (anterograde and retrograde) vesicular trafficking, abnormal trafficking of relevant receptors (i.e., BMPRI, BMPRII, IL-6R, gp130) and vasoactive mediators via alternative pathways that bypass the Golgi apparatus, have been implicated in the pathogenesis of PAH, as well (Sehgal and Lee, 2011).