Al Ghouleh et al. investigated the molecular mechanisms responsible for aberrant vascular remodeling occurring in pulmonary arterial hypertension (PAH) patients, demonstrating an up-regulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 (Nox1), an increase in reactive oxygen species (ROS) production and expression of bone morphogenetic protein (BMP) antagonist Gremlin1 (Grem1) in resistance vessels from PAH patients compared with non-PAH patients [71]. This evidence concerns the gene GREM1 and pulmonary arterial hypertension.