PASMC isolated from patients with heritable PAH (hPAH) known to be harbouring BMPR2 mutations have increased expression of OPG, and the OPG-binding partners, TRAIL and RANKL, compared to cells from controls (Lawrie et al., 2008, Hameed et al., 2012). Here, TNFRSF11B is linked to pulmonary arterial hypertension.