NOS3 and pulmonary arterial hypertension: In the MCT rat model of PAH, downregulation of miR-371b-5p was shown to increase apoptosis of PAECs via phosphatase and tensin homolog (PTEN)/ phosphoinositide 3-kinase (PI3K)/Akt signaling and to suppress endothelial nitric oxide synthase (eNOS) synthesis of nitric oxide which is a vasodilator (Zhu et al. 2018).