AKT1 and pulmonary arterial hypertension: In PASMCs isolated from the proximal pulmonary arteries, BMP4 inhibits proliferation, whereas in PASMCs from peripheral pulmonary arteries, it stimulates proliferation.188,189 Moreover, upregulation of miR-19a, miR-371b-5p, and METTL3 in PAH inhibit cell apoptosis by suppressing phosphatase and tension homolog, a key inhibitor of the PI3K/Akt pathway, in PASMCs and PAECs.190,191