TP53 and pulmonary arterial hypertension: More recently, the role of MEG3 (maternally expressed 3) in patients with pulmonary arterial hypertension was examined which revealed significantly reduced MEG3 expression levels in patients compared with healthy controls.44 In vitro siRNA silencing of MEG3 resulted in increased SMC proliferation and migration while mechanistic investigation revealed that MEG3 regulates the p53 pathway in PASMCs.45 Although several lncRNAs have been identified that control key aspects of SMC and EC function, very little is known about their role in atherosclerosis.