Based upon the high relative abundance of EP2 over IP (84-fold) and the fact that treprostinil has a 10-fold greater affinity at the EP2 receptor compared with the IP receptor (Whittle et al., 2012), it can be predicted that treprostinil will be more than two orders of magnitude (>800-fold) more active at EP2 versus IP receptors in PAH cells. Here, PTGER2 is linked to pulmonary arterial hypertension.