The research found that, compared to animals in 21% oxygen, mice exposed to 6 weeks of hypoxia had three times higher levels of Notch3 expression at both the mRNA and protein (ICD) levels in their lungs, with pulmonary artery pressures consistent with late-stage pulmonary hypertension (Thistlethwaite et al., 2010). This evidence concerns the gene NOTCH3 and pulmonary arterial hypertension.