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. Here, BMPR2 is linked to pulmonary arterial hypertension.