Emerging therapeutic targets in PAH. An improved understanding of the molecular and genetic mechanisms leading to PAH have provided translational opportunities for the development and testing of novel therapeutics agents. A number of emerging pathways amenable to therapeutic manipulation are summarized. 5-HT indicates serotonin; AMPK, AMP-activated protein kinase; BET, bromodomain and extra terminal domain; BMP9, bone morphogenetic protein 9; BMPR2, bone morphogenetic protein receptor type 2; CCR5, C-C chemokine receptor 5; DHEA, dehydroepiandrosterone; EC, endothelial cell; EPCs, endothelial progenitor cells; HDAC, histone deacetylases; LTB4, leukotriene B4; miRNA, microRNA; NFAT, nuclear factor of activated T cells; NF-κB, nuclear factor kappa light chain enhancer of activated B cells; PAH, pulmonary arterial hypertension; PPARγ, peroxisome proliferator-activated receptor γ; ROS, reactive oxygen species; TK, tyrosine kinase; TPH, tryptophan hydroxylase; VIP, vasoactive intestinal peptide.