Consistent with the previous reports indicating the increased ability of PAH PAEC to secrete mitogens for PASMC70, here we showed that GATA6-deficient PAEC not only increased proliferation of PASMC, but also induced other pathological changes, including downregulation of GATA6, SOD2, and BMPR2 in PASMC. The gene discussed is GATA6; the disease is pulmonary arterial hypertension.