Nicholas Morrell is the BHF Professor of Cardiopulmonary Medicine. He is a leading expert in the area of pulmonary arterial hypertension (PAH). His main contributions have been to define the key roles of the rennin-angiotensin and bone morphogenetic protein type II receptor (BMPR-II) signalling pathways in inherited forms of PAH and provide evidence of dysfunctional BMPR-II/Smad signalling in patients with sporadic disease. His laboratory have begun to pinpoint how defective BMPR-II signalling may also drive local inflammatory responses within the pulmonary circulation to work in concert with the loss of the growth suppressive effects of BMPR-II signalling.